Investigating water quality and growth of Cyprinus carpio fingerlings fed with different protein levels of diet in biofloc system

This study was conducted to investigate the effects of biofloc on water quality and growth efficiency of Cyprinus carpio fingerlings fed with different protein levels (23%, 27%, 31% and 35%) and a trial treatment with no biofloc in 8 weeks period. Mean oxygen rate (5.33) and pH (8.05) were investigated and were high in control treatment than BFT treatments. Total suspended solids was significantly high than control treatment (P<0.05). During feed experiment, good water quality was kept with biofloc development by adding sugar beet molasses. In biofloc treatments, ammonia, nitrate and nitrite amount decreased from the fourth week through time and biofloc developments, and their amount in biofloc treatments was lower than control treatment at the end of the experiment. Growth efficiency based on weight gain percentage and specific growth rate in fingerlings fed with 27% and 31% protein level was significantly higher than control treatment that fed with diet containing 35% protein (P<0.05). Totally, results of this study showed that in biofloc system, feeding of Cyprinus carpio with diet containing 27 and 31% protein has the best result in improvement of water quality and growth.