Evaluation of amino acids and fatty acids profiles of gammaridae extracts and its effects on Feed acceptability, utilization, growth performance and salinity stress resistance in Caspian roach (Rutilus caspicus, Yakovlev, 1870) fingerlings

The Caspian roach, Rutilus caspicus, is considered a new species for sustainable development and increasing the variety of cultured fish species in Iran. The aim of the present research was to study the effect of different levels of gammridae extracts on feed acceptability, utilization, growth performance and salinity stress resistance of Caspian roach. For this purpose, after evaluation of amino acids and fatty acids profiles, extract of gammaridae of Caspian sea shorelines was mixed with distilled water at two concentrations of (1:25 and 1:50) and sprayed on formulated feed by 2% before each feeding. Each concentration was tested in three replicates with a control. The experiment was carried out in 100-liter tanks which were filled by 80%. Twenty fingerlings of the Caspian roach weighted 4.3±0.5 g were introduced to each tank. Fish were fed to apparent satiation 3 times a day for 8 weeks. The speed of feed intake and effect of extract on feed acceptability were calculated in the first 15 minutes of feeding. At the end of the trial, growth parameters (final weight, weight gain, specific growth rate, condition factor, and feed conversion ratio) and resistance against salinity stress (15 mg/l or ppt) were measured. The results indicated that growth parameters significantly improved in fingerlings fed with diets containing gammaridae extract (P < 0.05), although no significant difference was found between two concentrations of extract (P> 0.05). In addition, the study findings showed that survival of fingerlings to salinity stress significantly increased after 72 hours (P< 0.05). The findings of the present study revealed that gammarus extract can increase feed acceptability and improve the growth in the Caspian roach due to its suitable amino acid and fatty acid profile.