Effects of different starter diets on growth indices of Caspian Kutum, Rutilus frisii kutum larvae (original) (raw)
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Aquaculture International, 2011
Kutum Rutilus frisii kutum is known as a valuable commercial species in the southern part of Caspian Sea. Artificial rearing of fry has been introduced as an alternative to supply kutum fry in order to restock the kutum population in the Caspian Sea. The aim of this study was to find the suitable time to transfer kutum larvae from live food to artificial feed. The experiment began on day 3 post-hatching and lasted for 21 days. Mean initial weight of larvae was 4.5 mg. Five experimental groups including Group A (zooplankton alone for 21 days), Group B (12 days zooplankton ? 9 days artificial feed), Group C (8 days zooplankton ? 13 days artificial feed), Group D (4 days zooplankton ? 17 days artificial feed) and Group E (artificial feed alone for 21 days) were considered for this experiment. According to the obtained results, the specific growth rate of kutum larvae varied from 8.01 to 13.58% day -1 , and the highest and lowest specific growth rate were found in A and E treatments, respectively. The lowest mean body weight (24.6 mg) was found in larvae fed on artificial feed for 21 days. However, survival rates of kutum larvae fed mixed zooplankton for 8 and 12 days (85.83 and 89.33%, respectively) were comparable with those of larvae fed live food during the entire experiment (91.6%). The lowest survival rate (69.16%) was found in larvae fed artificial feed during the entire experiment.
Morphological development of hatchery-reared Rutilus frissi kutum larvae
Most fish are poorly developed at hatching. They undergo important functional and morphological changes during the early larval period. This study was conducted to monitor the morphological changes of Caspian kutum Rutilus frisii kutum larvae in early life stages. Fertilized kutum eggs were incubated at 16-19ºC in 8 l glass incubators for 9.5 days. At first feeding (3 days after hatch) larvae were fed two times per day with egg yolk for 5 days, and then Artemia nauplii and egg yolk until day 30. The juveniles were then transferred to an outdoor fish hapa nets and further reared until day 60. Larval development, growth, and some morphological changes were described from day 0 to end of experiment. The results showed that there were 3 main stages and 18 sub-stages of ontogenetic development in Caspian kutum from hatching to juvenile stage. The most important change in these stages was change from endogenous to exogenous feeding. During post hatch development, the various organs gradually differentiated and became identifiable. Development of Morphology in Hatchery-Reared Rutilus Frisii Kutum Larvae 297