Mohamed Shariff | UPM - Universiti Putra Malaysia (original) (raw)

Papers by Mohamed Shariff

Research paper thumbnail of Tolerance of Tetraselmis tetrathele to High Ammonium Nitrogen and Its Effect on Growth Rate, Carotenoid, and Fatty Acids Productivity

Frontiers in Bioengineering and Biotechnology, Jan 28, 2021

Research paper thumbnail of Sustainable aquaculture of Asian arowana--a review

PubMed, Jul 1, 2016

Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly i... more Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly in Asian countries, and has been listed as one of the most highly endangered species. This is a freshwater, carnivorous, fairly large mouth breeding fish belonging to the family Osteoglossidae. Arowana can be found in different colour varieties such as green, red, silver and golden. Among these varieties, Malaysian golden is the most valuable fish and is endemic to the Krian riverine system, Malaysia. However, overexploitation, habitat change and pollution have caused a serious decline of this arowana variety. Recently, arowana aquaculture industry is expanding rapidly in Southeast Asian countries. However, difficulties in an accurate differentiation of sex and strains, causing imbalanced stocking ratios for optimum spawning, remain major obstacles in maximizing arowana production. In addition, problems in sustainable water sources of suitable quality and prevention of diseases need to be addressed. Recirculating aquaculture system (RAS) and bioremediation are two possible technologies that could be used to minimize pollution and ensure adequate high-quality water for arowana culture. In addition, the application of appropriate molecular markers for sex and strain identification is also an important strategy required for the improvement of captive breeding. This review discusses several issues such as the importance of arowana as an aquarium fish, its market demand, current problems in the arowana aquaculture industry and the possible technologies to enhance reproductive capacity and increase culture production. ?

Research paper thumbnail of Enhanced Growth Performance,Haemato-biochemical and Immune Parameters of Asian Seabass, Lates calcarifer (Bloch,1790) Fed Dietary Supplementation with Polygonum chinense

Asian Fisheries Science, 2019

The present study evaluated the effects of Polygonum chinense extract (PCE) on the growth perform... more The present study evaluated the effects of Polygonum chinense extract (PCE) on the growth performance, haemato-biochemical and innate immunity parameters of Asian seabass, Lates calcarifer (Bloch, 1790). The fish with an average weight of 9.5 ± 0.2 g were fed for 60 days using three supplementation diets of PCE at 0.2 %, 0.5 % and 1.0 %, and a non-supplemented diet as a control. Fish fed on 0.5 % PCE diet revealed significant higher body weight gain, specific growth rate, protein efficiency ratio, condition factor, and significantly lower feed conversion ratio. Dietary supplementation with 0.5 and 1.0 % showed a significant increase in red blood cell count and haemoglobin level, but the white blood cell count significantly increased only in 1.0 % diet. The alkaline phosphatase level significantly increased in fish group fed 0.2 and 0.5 % diets, but the aspartate transaminase level significantly decreases in 0.2 and 1.0 % groups. Meanwhile, all PCE supplemented diets showed significa...

Research paper thumbnail of Distinction of HPV-Type Viruses in Penaeus chinensis and Macrobrachium rosenbergii Using a DNA Probe

Asian Fisheries Science

Histological sections of hepatopancreas tissue from postlarval Macrobrachium rosenbergii from Mal... more Histological sections of hepatopancreas tissue from postlarval Macrobrachium rosenbergii from Malaysia infected with an HPV-type (HPV-Mac) virus were tested for possible virus homology with a DNA probe developed from an HPV-type virus (HPV-Chin) of Penaeus chinensis from Ko­rea. No reaction of the HPV-Chin probe was observed with HPV-Mac intranuclear inclusion bodies or infected cells. These findings, along with distinctive cytopathological differences between cells infected with HPV-Chin and HPV-Mac, indicate that these are distinctly different viruses within the parvovirus family.

Research paper thumbnail of {"__content__"=>"Serum cortisol level and survival rate of juvenile following exposure to different salinities.", "i"=>{"__content__"=>"Epinephelus fuscoguttatus"}}

Veterinary world, 2018

Brown-marbled grouper is a premium marine food fish with high demand in Asia. In fish, stress due... more Brown-marbled grouper is a premium marine food fish with high demand in Asia. In fish, stress due to environmental changes such as fluctuations in the salinity can result in increased cortisol level. Stress in fish increases susceptibility to diseases ultimately resulting in death. Therefore, the aim of this study was to investigate the salinity tolerance of and their survival in lower salinities. In this study, grouper juveniles (92.43±standard error of the mean 0.51 mm) maintained in 31 ppt seawater were transferred into five tanks with seawater diluted to 25, 20, 15, 10, and 5 ppt. The salinity of the control group was not changed and was maintained at 31 ppt. Serum cortisol was measured using ELISA at 0, 30, 60, and 120 min after the fish were transferred to the different concentrations of salinity. The survival percentage was recorded for 14 days following the transfer and the results revealed that serum cortisol of fish in a high change in salinity (15, 10, and 5 ppt) was sign...

Research paper thumbnail of Enhancement of lipid production in two marine microalgae under different levels of nitrogen and phosphorus deficiency

PubMed, Jul 1, 2016

Microalgae are important food sources for aquaculture animals. Among the different factors which ... more Microalgae are important food sources for aquaculture animals. Among the different factors which influence the biochemical composition of microalgae, nitrogen and phosphorus are two of the most important nutrient sources for growth and development. The present study aimed to assess the effects of nitrogen and phosphorus deficiency on lipid production of Chlorella sp. and Chaetoceros calcitrans. Early stationary phase culture of these species were exposed to different stress levels of nitrogen and phosphorus (25%, 50% and 75% of the full NO(3)-N and PO(4)-P concentration in the Conway media), and solvent extraction and gas-liquid chromatography methods were performed for analysis of lipid and fatty acid composition. The results revealed that lipid production in these two species significantly increased (P<0.05) as nitrogen and phosphorus decreased. The fatty acid proportion remained unaffected under nitrogen deficiency, while phosphorus limitation resulted in a decrease of saturated fatty acids and promoted a higher content of omega-3 fatty acids in these species. The protein and carbohydrate levels were also altered under limited nutrients. Therefore, these conditions could be used for enhanced lipid production in microalgae for aquaculture and other industrial applications.

Research paper thumbnail of Health management in tropical aquaculture systems

Health management strategies are very important in aquaculture. In Asia, health management practi... more Health management strategies are very important in aquaculture. In Asia, health management practices are broadly similar for the various aquatic species that are cultured. These focus mainly on maintaining the good health of the organisms throughout the life cycle. Good health management is based on an understanding of the interactions between the environment (water), the host, and the pathogens. In an ideal system, the three factors are balanced to offset a disease process. This balance is difficult to maintain in an intensive culture system and significant mortalities usually result. The outbreak of disease is thus related to poor health management. This paper deals with the health management practices applicable to the hatchery and grow-out stages of shrimp and fishes cultured in the tropics.

Research paper thumbnail of Occurrence of parasites at the fish breeding stations in peninsular Malaysia and their control

In order to enhance the development of aquaculture in Malaysia, the Government has 8 freshwater f... more In order to enhance the development of aquaculture in Malaysia, the Government has 8 freshwater fish breeding stations to provide fish seed for farmers. In the past, these breeding stations have had occasional problems of fish mortalities. A study was conducted to investigate the causes of such fish mortalities at the breeding stations. The results revealed that the common causes in the order of frequency of occurrence were; Ichthyophehirius multifilHs, Lernaea cyprinacea, monogenetic trematodes (Gyrodactylus and DactylOgyrus), Trichodina, fungal infection and OOdinium. During the period 1981 - 1982, an average number of three outbreaks occurred in the fish breeding stations per year. On the occurrence of such outbreaks the average mortalities incurred were associated With Trichodina (60%), monogenetic trematodes (58.5%), Lernaea clPrinaceae (55.5%), fungal infections (50.9%). Ichtbyopthirius multifiliis (35%) and Oodinium (20%). Low temperatures was found to be an additional contribu.ting factor for the mortalities at one of the highlands statibns where the temperature ranged between 17 - 24°C and the ~rtality rate was as high as 40% in one year i.e. 1982. In the' other stations with higher temperatures (26 -32°C) the average mortality was only 10%. Myxobolull sp. was found on common carp. This is the first record of the occurrence of Myxobolus sp. in cultured fish in Malaysia. Argulus'japonicus was also recorded at the breeding stations. The possible sources of ectoparasites in the breeding stations is discussed and the prevention and control of such ectoparasites is also presented.

Research paper thumbnail of Antibiotic susceptibility testing of aquaculture associated bacteria originating from integrated farming systems in the Mekong River Delta, Viet Nam

Research paper thumbnail of Sustainable aquaculture of Asian arowana: a review

Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly i... more Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly in Asian countries, and has been listed as one of the most highly endangered species. This is a freshwater, carnivorous, fairly large mouth breeding fish belonging to the family Osteoglossidae. Arowana can be found in different colour varieties such as green, red, silver and golden. Among these varieties, Malaysian golden is the most valuable fish and is endemic to the Krian riverine system, Malaysia. However, overexploitation, habitat change and pollution have caused a serious decline of this arowana variety. Recently, arowana aquaculture industry is expanding rapidly in Southeast Asian countries. However, difficulties in an accurate differentiation of sex and strains, causing imbalanced stocking ratios for optimum spawning, remain major obstacles in maximizing arowana production. In addition, problems in sustainable water sources of suitable quality and prevention of diseases need to be...

Research paper thumbnail of Use of Microalgae Pigments in Aquaculture

Aquaculture sector shows the fastest growth among the global food production industries. However,... more Aquaculture sector shows the fastest growth among the global food production industries. However, nutrition and diseases are two important hurdles that need to be addressed to propel the industry forward. Consistent supply of high-quality feed for growing larvae of important aquaculture species is one of the bottlenecks of the local larviculture industry. Microalgal pigments containing carotenoids, phycobiliproteins and chlorophylls are highly nutritious functional foods containing high antioxidant biomolecules associated with fast growth, high immunity, enhanced pigmentation and high productivity. Their high contents of lipids and fatty acids make them valuable alternatives for replacement of fish meals in livestock and fish feeds. Polyunsaturated fatty acids (PUFAs), functional amino acids, vitamins and other biomolecules associated with health are also found in many microalgae species. Major pigments such as astaxanthin, lutein, beta-carotene, chlorophylls, and phycobiliproteins ...

Research paper thumbnail of Use of beneficial bacteria to increase shrimp production

'9-' 44Ut '9T he use of imported commercial microbial products in improving water quality and con... more '9-' 44Ut '9T he use of imported commercial microbial products in improving water quality and controlling microbial infections in shrimps has shown promising results. However, these products showed insignificant increase in shrimp production, probably due to unsuitable environmental conditions for the proliferation of exotic microorganisms. For bio-safety reasons as well as to avoid sudden changes in the microbial flora of the ecosystem, our research focused on the use of indigenous microorganism to improve water quality in shrimp culture ponds and to enhance shrimp health. In addition, the use of imported bacterial products adds to the import bill of the country. Indigenous Bacillus spp. isolated from local marine waters were used as potential candidates for the bioremediation product and their selection was based on their ability to secrete extracellular enzymes, express competitive exclusion, high survival rate, non-pathogenic to shrimp larvae, and ability to grow fast. The effect of combination of two Bacillus spp. showed that rate of ammonia reduction was higher compared to individual species under simulated shrimp pond conditions. In addition shrimp fed with bacterial additives showed better growth and survival compared to the control fed with commercial shrimp feed. Furthermore, shrimp fed on bacterial supplemented diet had higher survival rate when challenged with the white spot syndrome virus (WSSV) whereas shrimp fed on artificial diet showed higher mortality. Bacillus spp. also demonstrated the ability to suppress the growth of pathogenic bacteria isolated from Anemia cyst and shrimp ponds. Thus, utilization of these bacteria for biocontrol of pathogenic vibrios might be a good alternative to antibiotics that has ecotoxicological implications and ill effects on human health. These bacterial have been proven to be 'non-pathogenic to shrimp and might be useful in formulating an effective bioremediation product for shrimp culture. In addition, the same bioremediation products can be used in other aquaculture activities such as fish/shrimp hatchery, aquarium, and other aquaculture systems. Research is now being conducted to mass-produce the bacteria consortium for commercial purposes.

Research paper thumbnail of Diseases in Asian aquaculture : proceedings of the first symposium on diseases in Asian aquaculture, 26-29 November 1990, Bali, Indonesia

Research paper thumbnail of Viewpoint: SARS-CoV-2 (The Cause of COVID-19 in Humans) is Not Known to Infect Aquatic Food Animals nor Contaminate Their Products

Asian Fisheries Science, 2020

This paper is in response to the need for clear communication regarding the risk of transmission ... more This paper is in response to the need for clear communication regarding the risk of transmission of the novel Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes COVID-19 in humans and the general societal concern of potential contamination, of aquatic animals used as food or their products, with the virus. SARS-CoV-2 belongs to the family Coronaviridae and genus Betacoronavirus. Betacoronaviruses are only reported to infect mammals. Currently there is no evidence to suggest that SARS-CoV-2 can infect aquatic food animals (e.g. finfish, crustaceans, molluscs, amphibians) and therefore these animals do not play an epidemiological role in spreading COVID-19 to humans. Aquatic food animals and their products, like any other surface, may potentially become contaminated with SARS-CoV-2, especially when handled by people who are infected with the virus. Nevertheless, with proper food handling and sanitation, the likelihood of contamination of aquatic animals or their products with SARS-CoV-2 should be negligible. The COVID-19 pandemic may negatively affect livelihoods, food security and nutrition for populations that rely on aquatic animals as a source of food or income. On a positive side, however, COVID-19 outbreaks may lead to an increase in local community utilization of aquatic food animals or their products due to limited transportation or limited supplies of alternative sources of animal proteins.

Research paper thumbnail of Residual quantification and oxidative stress induced by malachite green after subacute and sublethal exposure in red tilapia

Veterinary World, 2019

Background and Aim: Malachite green (MG) is an effective antiparasitic and antifungal chemical fo... more Background and Aim: Malachite green (MG) is an effective antiparasitic and antifungal chemical for treatment of fish. However, MG is reported to be a potential carcinogen. Yet, it is widely used in aquaculture despite its prohibition for use in food-producing animals by the EU and USFDA. The present study quantified MG residues and evaluated the oxidative stress in red tilapia when exposed to subacute and sublethal concentrations of MG. Materials and Methods: Red tilapia exposed to subacute (0.105 mg/L for 20 days) and sublethal (0.053 mg/L for 60 days) concentrations were evaluated for total plasma protein, total immunoglobulin, nitroblue tetrazolium activity, malondialdehyde, reduced glutathione (GSH), and catalase (CAT) activity levels. The residues of MG and leuco-MG (LMG) were also quantified in the fish muscles using liquid chromatography-tandem mass spectrometry. Results: Fish exposed to subacute concentration showed higher CAT on day 10 in the liver and days 5 and 15 in the ...

Research paper thumbnail of Littoral and limnetic phytoplankton distribution and biodiversity in a tropical man-made lake, Malaysia

Advanced Studies in Biology, 2014

The distribution of the phytoplankton community in different zones of Putrajaya Lake, Malaysia wa... more The distribution of the phytoplankton community in different zones of Putrajaya Lake, Malaysia was analyzed from October 2009 to September 2010 to examine the zonal-distribution relationship. Three stations representing three different lake zones namely Station 1 (littoral zone), Station 2 (sub-littoral zone) and Station 3 (limnetic zone) were selected. Water transparency, temperature, pH, dissolved oxygen and conductivity were found to be important factors characterizing each zone. A total of 148 species from 77 genera were recorded throughout the sampling duration from October 2009 until September 2010. During this period, Chlorophyta was the most abundant group (59% of the total phytoplankton), followed by Pyrrhophyta (15%), Cyanobacteria (11%), Bacillariophyceae (9%), Chrysophyceae (3%), Cryptophyta (2%) and Euglenophyta (1%). The highest mean density of phytoplankton was recorded in the limnetic zone (433.94 ± 18.29 cells ml-1), followed by sub-littoral (292.94 ± 18.61 cells ml-1) and littoral zone (199.58 ± 13.56 cells ml-1). There was a significant difference in the Shannon-Wiener diversity index for phytoplankton diversity and abundance in all three zones (p<0.05) with limnetic zone demonstrating the highest species diversity. 150 Asma' Jamal et al. Species commonly found in the sub-littoral area also dominated both littoral and limnetic phytoplankton communities suggesting that sub-littoral zone acted as an interphase for phytoplankton adaptation and migration between the two different zones. The findings suggest that spatial distribution and diversity of the phytoplankton community can be affected significantly by local lake zonation characterized by environmental variations.

Research paper thumbnail of Cage culture in Malaysia: an overview

Research paper thumbnail of Health management in Asian aquaculture: proceedings of the Regional Expert Consultation on Aquaculture Health Management in Asia and Pacific, Serdang, Malaysia, 22-24 May, 1995

Research paper thumbnail of Women in fisheries in Asia

Research paper thumbnail of The use of chemicals in aquaculture in Malaysia and Singapore

Aquaculture is an increasingly important force in both the Malaysian as well as the Singaporean e... more Aquaculture is an increasingly important force in both the Malaysian as well as the Singaporean economies. In recent years, Singapore has focused on the aquarium fish trade, making it one of the largest ornamental fish production and transhipment centers in the world. Similarly, the Malaysian aquaculture industry has made rapid strides in the last few years and is poised to become a major contributor to the national fish supply by the early part of the next century. A significant trend in both countries has been the growing intensification of culture systems to achieve higher production per unit area. This has led to a greater occurrence of disease, particularly among aquarium fish, shrimp and marine fish farms. To obviate and control these diseases, there has been a concurrent increase in the use of chemotherapeutants. The three major groups of commonly used chemotherapeutants are: topical disinfectants, antimicrobials and probiotics. There is a wide range of topical disinfectants used by aquafarmers. The most common of these include lime, teaseed cake, formalin, benzalkonium chloride, acriflavine, malachite green, hypochlorite and poly-vinyl pyrrolidine. Of these, lime and teaseed cake are used exclusively in ponds, and acriflavine and malachite green only in hatcheries, while the others are used in both systems. Antimicrobials being used include sulfonamides, tetracyclines, nitrofurans, chloramphenicol, oxolinic acid and virginiamycin. A number of other chemotherapeutants are also used, albeit on a limited basis. The current concerns surrounding the use of chemotherapeutants and the legislative framework surrounding their sale and distribution are also discussed.

Research paper thumbnail of Tolerance of Tetraselmis tetrathele to High Ammonium Nitrogen and Its Effect on Growth Rate, Carotenoid, and Fatty Acids Productivity

Frontiers in Bioengineering and Biotechnology, Jan 28, 2021

Research paper thumbnail of Sustainable aquaculture of Asian arowana--a review

PubMed, Jul 1, 2016

Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly i... more Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly in Asian countries, and has been listed as one of the most highly endangered species. This is a freshwater, carnivorous, fairly large mouth breeding fish belonging to the family Osteoglossidae. Arowana can be found in different colour varieties such as green, red, silver and golden. Among these varieties, Malaysian golden is the most valuable fish and is endemic to the Krian riverine system, Malaysia. However, overexploitation, habitat change and pollution have caused a serious decline of this arowana variety. Recently, arowana aquaculture industry is expanding rapidly in Southeast Asian countries. However, difficulties in an accurate differentiation of sex and strains, causing imbalanced stocking ratios for optimum spawning, remain major obstacles in maximizing arowana production. In addition, problems in sustainable water sources of suitable quality and prevention of diseases need to be addressed. Recirculating aquaculture system (RAS) and bioremediation are two possible technologies that could be used to minimize pollution and ensure adequate high-quality water for arowana culture. In addition, the application of appropriate molecular markers for sex and strain identification is also an important strategy required for the improvement of captive breeding. This review discusses several issues such as the importance of arowana as an aquarium fish, its market demand, current problems in the arowana aquaculture industry and the possible technologies to enhance reproductive capacity and increase culture production. ?

Research paper thumbnail of Enhanced Growth Performance,Haemato-biochemical and Immune Parameters of Asian Seabass, Lates calcarifer (Bloch,1790) Fed Dietary Supplementation with Polygonum chinense

Asian Fisheries Science, 2019

The present study evaluated the effects of Polygonum chinense extract (PCE) on the growth perform... more The present study evaluated the effects of Polygonum chinense extract (PCE) on the growth performance, haemato-biochemical and innate immunity parameters of Asian seabass, Lates calcarifer (Bloch, 1790). The fish with an average weight of 9.5 ± 0.2 g were fed for 60 days using three supplementation diets of PCE at 0.2 %, 0.5 % and 1.0 %, and a non-supplemented diet as a control. Fish fed on 0.5 % PCE diet revealed significant higher body weight gain, specific growth rate, protein efficiency ratio, condition factor, and significantly lower feed conversion ratio. Dietary supplementation with 0.5 and 1.0 % showed a significant increase in red blood cell count and haemoglobin level, but the white blood cell count significantly increased only in 1.0 % diet. The alkaline phosphatase level significantly increased in fish group fed 0.2 and 0.5 % diets, but the aspartate transaminase level significantly decreases in 0.2 and 1.0 % groups. Meanwhile, all PCE supplemented diets showed significa...

Research paper thumbnail of Distinction of HPV-Type Viruses in Penaeus chinensis and Macrobrachium rosenbergii Using a DNA Probe

Asian Fisheries Science

Histological sections of hepatopancreas tissue from postlarval Macrobrachium rosenbergii from Mal... more Histological sections of hepatopancreas tissue from postlarval Macrobrachium rosenbergii from Malaysia infected with an HPV-type (HPV-Mac) virus were tested for possible virus homology with a DNA probe developed from an HPV-type virus (HPV-Chin) of Penaeus chinensis from Ko­rea. No reaction of the HPV-Chin probe was observed with HPV-Mac intranuclear inclusion bodies or infected cells. These findings, along with distinctive cytopathological differences between cells infected with HPV-Chin and HPV-Mac, indicate that these are distinctly different viruses within the parvovirus family.

Research paper thumbnail of {"__content__"=>"Serum cortisol level and survival rate of juvenile following exposure to different salinities.", "i"=>{"__content__"=>"Epinephelus fuscoguttatus"}}

Veterinary world, 2018

Brown-marbled grouper is a premium marine food fish with high demand in Asia. In fish, stress due... more Brown-marbled grouper is a premium marine food fish with high demand in Asia. In fish, stress due to environmental changes such as fluctuations in the salinity can result in increased cortisol level. Stress in fish increases susceptibility to diseases ultimately resulting in death. Therefore, the aim of this study was to investigate the salinity tolerance of and their survival in lower salinities. In this study, grouper juveniles (92.43±standard error of the mean 0.51 mm) maintained in 31 ppt seawater were transferred into five tanks with seawater diluted to 25, 20, 15, 10, and 5 ppt. The salinity of the control group was not changed and was maintained at 31 ppt. Serum cortisol was measured using ELISA at 0, 30, 60, and 120 min after the fish were transferred to the different concentrations of salinity. The survival percentage was recorded for 14 days following the transfer and the results revealed that serum cortisol of fish in a high change in salinity (15, 10, and 5 ppt) was sign...

Research paper thumbnail of Enhancement of lipid production in two marine microalgae under different levels of nitrogen and phosphorus deficiency

PubMed, Jul 1, 2016

Microalgae are important food sources for aquaculture animals. Among the different factors which ... more Microalgae are important food sources for aquaculture animals. Among the different factors which influence the biochemical composition of microalgae, nitrogen and phosphorus are two of the most important nutrient sources for growth and development. The present study aimed to assess the effects of nitrogen and phosphorus deficiency on lipid production of Chlorella sp. and Chaetoceros calcitrans. Early stationary phase culture of these species were exposed to different stress levels of nitrogen and phosphorus (25%, 50% and 75% of the full NO(3)-N and PO(4)-P concentration in the Conway media), and solvent extraction and gas-liquid chromatography methods were performed for analysis of lipid and fatty acid composition. The results revealed that lipid production in these two species significantly increased (P<0.05) as nitrogen and phosphorus decreased. The fatty acid proportion remained unaffected under nitrogen deficiency, while phosphorus limitation resulted in a decrease of saturated fatty acids and promoted a higher content of omega-3 fatty acids in these species. The protein and carbohydrate levels were also altered under limited nutrients. Therefore, these conditions could be used for enhanced lipid production in microalgae for aquaculture and other industrial applications.

Research paper thumbnail of Health management in tropical aquaculture systems

Health management strategies are very important in aquaculture. In Asia, health management practi... more Health management strategies are very important in aquaculture. In Asia, health management practices are broadly similar for the various aquatic species that are cultured. These focus mainly on maintaining the good health of the organisms throughout the life cycle. Good health management is based on an understanding of the interactions between the environment (water), the host, and the pathogens. In an ideal system, the three factors are balanced to offset a disease process. This balance is difficult to maintain in an intensive culture system and significant mortalities usually result. The outbreak of disease is thus related to poor health management. This paper deals with the health management practices applicable to the hatchery and grow-out stages of shrimp and fishes cultured in the tropics.

Research paper thumbnail of Occurrence of parasites at the fish breeding stations in peninsular Malaysia and their control

In order to enhance the development of aquaculture in Malaysia, the Government has 8 freshwater f... more In order to enhance the development of aquaculture in Malaysia, the Government has 8 freshwater fish breeding stations to provide fish seed for farmers. In the past, these breeding stations have had occasional problems of fish mortalities. A study was conducted to investigate the causes of such fish mortalities at the breeding stations. The results revealed that the common causes in the order of frequency of occurrence were; Ichthyophehirius multifilHs, Lernaea cyprinacea, monogenetic trematodes (Gyrodactylus and DactylOgyrus), Trichodina, fungal infection and OOdinium. During the period 1981 - 1982, an average number of three outbreaks occurred in the fish breeding stations per year. On the occurrence of such outbreaks the average mortalities incurred were associated With Trichodina (60%), monogenetic trematodes (58.5%), Lernaea clPrinaceae (55.5%), fungal infections (50.9%). Ichtbyopthirius multifiliis (35%) and Oodinium (20%). Low temperatures was found to be an additional contribu.ting factor for the mortalities at one of the highlands statibns where the temperature ranged between 17 - 24°C and the ~rtality rate was as high as 40% in one year i.e. 1982. In the' other stations with higher temperatures (26 -32°C) the average mortality was only 10%. Myxobolull sp. was found on common carp. This is the first record of the occurrence of Myxobolus sp. in cultured fish in Malaysia. Argulus'japonicus was also recorded at the breeding stations. The possible sources of ectoparasites in the breeding stations is discussed and the prevention and control of such ectoparasites is also presented.

Research paper thumbnail of Antibiotic susceptibility testing of aquaculture associated bacteria originating from integrated farming systems in the Mekong River Delta, Viet Nam

Research paper thumbnail of Sustainable aquaculture of Asian arowana: a review

Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly i... more Asian arowana, Scleropages formosus is a highly valued aquarium fish in the world, particularly in Asian countries, and has been listed as one of the most highly endangered species. This is a freshwater, carnivorous, fairly large mouth breeding fish belonging to the family Osteoglossidae. Arowana can be found in different colour varieties such as green, red, silver and golden. Among these varieties, Malaysian golden is the most valuable fish and is endemic to the Krian riverine system, Malaysia. However, overexploitation, habitat change and pollution have caused a serious decline of this arowana variety. Recently, arowana aquaculture industry is expanding rapidly in Southeast Asian countries. However, difficulties in an accurate differentiation of sex and strains, causing imbalanced stocking ratios for optimum spawning, remain major obstacles in maximizing arowana production. In addition, problems in sustainable water sources of suitable quality and prevention of diseases need to be...

Research paper thumbnail of Use of Microalgae Pigments in Aquaculture

Aquaculture sector shows the fastest growth among the global food production industries. However,... more Aquaculture sector shows the fastest growth among the global food production industries. However, nutrition and diseases are two important hurdles that need to be addressed to propel the industry forward. Consistent supply of high-quality feed for growing larvae of important aquaculture species is one of the bottlenecks of the local larviculture industry. Microalgal pigments containing carotenoids, phycobiliproteins and chlorophylls are highly nutritious functional foods containing high antioxidant biomolecules associated with fast growth, high immunity, enhanced pigmentation and high productivity. Their high contents of lipids and fatty acids make them valuable alternatives for replacement of fish meals in livestock and fish feeds. Polyunsaturated fatty acids (PUFAs), functional amino acids, vitamins and other biomolecules associated with health are also found in many microalgae species. Major pigments such as astaxanthin, lutein, beta-carotene, chlorophylls, and phycobiliproteins ...

Research paper thumbnail of Use of beneficial bacteria to increase shrimp production

'9-' 44Ut '9T he use of imported commercial microbial products in improving water quality and con... more '9-' 44Ut '9T he use of imported commercial microbial products in improving water quality and controlling microbial infections in shrimps has shown promising results. However, these products showed insignificant increase in shrimp production, probably due to unsuitable environmental conditions for the proliferation of exotic microorganisms. For bio-safety reasons as well as to avoid sudden changes in the microbial flora of the ecosystem, our research focused on the use of indigenous microorganism to improve water quality in shrimp culture ponds and to enhance shrimp health. In addition, the use of imported bacterial products adds to the import bill of the country. Indigenous Bacillus spp. isolated from local marine waters were used as potential candidates for the bioremediation product and their selection was based on their ability to secrete extracellular enzymes, express competitive exclusion, high survival rate, non-pathogenic to shrimp larvae, and ability to grow fast. The effect of combination of two Bacillus spp. showed that rate of ammonia reduction was higher compared to individual species under simulated shrimp pond conditions. In addition shrimp fed with bacterial additives showed better growth and survival compared to the control fed with commercial shrimp feed. Furthermore, shrimp fed on bacterial supplemented diet had higher survival rate when challenged with the white spot syndrome virus (WSSV) whereas shrimp fed on artificial diet showed higher mortality. Bacillus spp. also demonstrated the ability to suppress the growth of pathogenic bacteria isolated from Anemia cyst and shrimp ponds. Thus, utilization of these bacteria for biocontrol of pathogenic vibrios might be a good alternative to antibiotics that has ecotoxicological implications and ill effects on human health. These bacterial have been proven to be 'non-pathogenic to shrimp and might be useful in formulating an effective bioremediation product for shrimp culture. In addition, the same bioremediation products can be used in other aquaculture activities such as fish/shrimp hatchery, aquarium, and other aquaculture systems. Research is now being conducted to mass-produce the bacteria consortium for commercial purposes.

Research paper thumbnail of Diseases in Asian aquaculture : proceedings of the first symposium on diseases in Asian aquaculture, 26-29 November 1990, Bali, Indonesia

Research paper thumbnail of Viewpoint: SARS-CoV-2 (The Cause of COVID-19 in Humans) is Not Known to Infect Aquatic Food Animals nor Contaminate Their Products

Asian Fisheries Science, 2020

This paper is in response to the need for clear communication regarding the risk of transmission ... more This paper is in response to the need for clear communication regarding the risk of transmission of the novel Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes COVID-19 in humans and the general societal concern of potential contamination, of aquatic animals used as food or their products, with the virus. SARS-CoV-2 belongs to the family Coronaviridae and genus Betacoronavirus. Betacoronaviruses are only reported to infect mammals. Currently there is no evidence to suggest that SARS-CoV-2 can infect aquatic food animals (e.g. finfish, crustaceans, molluscs, amphibians) and therefore these animals do not play an epidemiological role in spreading COVID-19 to humans. Aquatic food animals and their products, like any other surface, may potentially become contaminated with SARS-CoV-2, especially when handled by people who are infected with the virus. Nevertheless, with proper food handling and sanitation, the likelihood of contamination of aquatic animals or their products with SARS-CoV-2 should be negligible. The COVID-19 pandemic may negatively affect livelihoods, food security and nutrition for populations that rely on aquatic animals as a source of food or income. On a positive side, however, COVID-19 outbreaks may lead to an increase in local community utilization of aquatic food animals or their products due to limited transportation or limited supplies of alternative sources of animal proteins.

Research paper thumbnail of Residual quantification and oxidative stress induced by malachite green after subacute and sublethal exposure in red tilapia

Veterinary World, 2019

Background and Aim: Malachite green (MG) is an effective antiparasitic and antifungal chemical fo... more Background and Aim: Malachite green (MG) is an effective antiparasitic and antifungal chemical for treatment of fish. However, MG is reported to be a potential carcinogen. Yet, it is widely used in aquaculture despite its prohibition for use in food-producing animals by the EU and USFDA. The present study quantified MG residues and evaluated the oxidative stress in red tilapia when exposed to subacute and sublethal concentrations of MG. Materials and Methods: Red tilapia exposed to subacute (0.105 mg/L for 20 days) and sublethal (0.053 mg/L for 60 days) concentrations were evaluated for total plasma protein, total immunoglobulin, nitroblue tetrazolium activity, malondialdehyde, reduced glutathione (GSH), and catalase (CAT) activity levels. The residues of MG and leuco-MG (LMG) were also quantified in the fish muscles using liquid chromatography-tandem mass spectrometry. Results: Fish exposed to subacute concentration showed higher CAT on day 10 in the liver and days 5 and 15 in the ...

Research paper thumbnail of Littoral and limnetic phytoplankton distribution and biodiversity in a tropical man-made lake, Malaysia

Advanced Studies in Biology, 2014

The distribution of the phytoplankton community in different zones of Putrajaya Lake, Malaysia wa... more The distribution of the phytoplankton community in different zones of Putrajaya Lake, Malaysia was analyzed from October 2009 to September 2010 to examine the zonal-distribution relationship. Three stations representing three different lake zones namely Station 1 (littoral zone), Station 2 (sub-littoral zone) and Station 3 (limnetic zone) were selected. Water transparency, temperature, pH, dissolved oxygen and conductivity were found to be important factors characterizing each zone. A total of 148 species from 77 genera were recorded throughout the sampling duration from October 2009 until September 2010. During this period, Chlorophyta was the most abundant group (59% of the total phytoplankton), followed by Pyrrhophyta (15%), Cyanobacteria (11%), Bacillariophyceae (9%), Chrysophyceae (3%), Cryptophyta (2%) and Euglenophyta (1%). The highest mean density of phytoplankton was recorded in the limnetic zone (433.94 ± 18.29 cells ml-1), followed by sub-littoral (292.94 ± 18.61 cells ml-1) and littoral zone (199.58 ± 13.56 cells ml-1). There was a significant difference in the Shannon-Wiener diversity index for phytoplankton diversity and abundance in all three zones (p<0.05) with limnetic zone demonstrating the highest species diversity. 150 Asma' Jamal et al. Species commonly found in the sub-littoral area also dominated both littoral and limnetic phytoplankton communities suggesting that sub-littoral zone acted as an interphase for phytoplankton adaptation and migration between the two different zones. The findings suggest that spatial distribution and diversity of the phytoplankton community can be affected significantly by local lake zonation characterized by environmental variations.

Research paper thumbnail of Cage culture in Malaysia: an overview

Research paper thumbnail of Health management in Asian aquaculture: proceedings of the Regional Expert Consultation on Aquaculture Health Management in Asia and Pacific, Serdang, Malaysia, 22-24 May, 1995

Research paper thumbnail of Women in fisheries in Asia

Research paper thumbnail of The use of chemicals in aquaculture in Malaysia and Singapore

Aquaculture is an increasingly important force in both the Malaysian as well as the Singaporean e... more Aquaculture is an increasingly important force in both the Malaysian as well as the Singaporean economies. In recent years, Singapore has focused on the aquarium fish trade, making it one of the largest ornamental fish production and transhipment centers in the world. Similarly, the Malaysian aquaculture industry has made rapid strides in the last few years and is poised to become a major contributor to the national fish supply by the early part of the next century. A significant trend in both countries has been the growing intensification of culture systems to achieve higher production per unit area. This has led to a greater occurrence of disease, particularly among aquarium fish, shrimp and marine fish farms. To obviate and control these diseases, there has been a concurrent increase in the use of chemotherapeutants. The three major groups of commonly used chemotherapeutants are: topical disinfectants, antimicrobials and probiotics. There is a wide range of topical disinfectants used by aquafarmers. The most common of these include lime, teaseed cake, formalin, benzalkonium chloride, acriflavine, malachite green, hypochlorite and poly-vinyl pyrrolidine. Of these, lime and teaseed cake are used exclusively in ponds, and acriflavine and malachite green only in hatcheries, while the others are used in both systems. Antimicrobials being used include sulfonamides, tetracyclines, nitrofurans, chloramphenicol, oxolinic acid and virginiamycin. A number of other chemotherapeutants are also used, albeit on a limited basis. The current concerns surrounding the use of chemotherapeutants and the legislative framework surrounding their sale and distribution are also discussed.