Effect of salinity and protein level on haematological, physiological changes and growth of hybrid tilapia (Oreochromis mossambicus × Oreochromis niloticus)

Abstract

The experiment was conducted to determine the optimal salinity and dietary protein levels on physiological, haematological changes and growth. The juveniles (Oreochromis mossambicus × Oreochromis niloticus) were stocked at 20 fish/ 50L. The initial weight was (2.1 ± 0.02) and reserved in salinity 0, 10, 20 and 35 ppt (S1, S2, S3 and S4 respectively) with 30% (P1) and 40% (P2) dietary protein levels for 45 days. The harvesting weight and SGR were not significantly (P > 0.05) varied in connecting S2-S3/P1 or in between S2-S3/P2. The food consumptions were significantly (P < 0.05) increased with decreasing protein levels and increasing salinities up to 0 ppt. The survival rates were not significantly (P > 0.05) differed among whole treatments. The lowest FCR and highest muscular hydration were achieved at intermediate salinities with low protein diet. No oblivious changes were occurred in Hct%, Hb, plasma protein, muscles and liver protein levels in whole treatments. Furthermore, the plasma cortisol and glucose levels were tended to high at higher salinity but did not significantly (P > 0.05) different among all treatments. The physico-chemical parameters of water were at satisfactory levels throughout the study. The aforementioned results showed that environmental salinity (0-35 ppt) do not adverse affect on growth and biochemical changes and also no required high protein levels in diets at any respected salinities.