Growth and Physiological Responses of Nile Tilapia Oreochromis niloticus and Hybrid Red Tilapia (O. mossambicus ♂ X O. niloticus♀) by Changes in Salinity of Rearing Water (original) (raw)

This research aims to study the adaptation availability of two types of tilapia (Nile tilapia, Red tilapia), reared in different levels of salinity on growth performance, feed efficiency, nutrient body content, survival rates, and physiological changes related to osmoregulation. The experiment was conducted using 90 fish with average weight of 10.55 g for each type of tilapia, divided equally on 18 concrete ponds at a density rate of 10 fish per pond. Three levels of water salinity were used: fresh water 11.5 ppt, brackish water 17 ppt and saline water 28 ppt. Fish were fed on diet containing almost 32% protein and gross energy 414.8 kcal /100g. The feed allowance was 4% of fish body weight. The results showed that red tilapia were better than Nile tilapia in growth performance, feed efficiency and survival rates under different levels of salinity. Increasing salinity reduced growth performance, feed efficiency and survival rates of Nile tilapia. Increasing salinity increased the body content of protein ash, and reduced the body content of fat for both Nile tilapia and red tilapia. The results showed physiological changes of both Nile tilapia and red tilapia for hemoglubin, hematocrite, total protein, sodium, potassium, and cortisol by increasing level of salinity. Increase of salinity levels increased the level of glucose in Red tilapia, while opposite trend was observed in Nile tilapia. The present study as demonstrated, suggests the possibility of culturing Nile tilapia, in both fresh and low brackish water environments. It could be concluded that using saline and brackish water for rearing hybrid red tilapia is a promising solution due to the scarcity of fresh water.