Effect of different levels of dietary protein on growth parameters of Oscar fish (Astronotus ocellatus Agassiz, 1831)

An experiment was designed to determine the optimum dietary protein level of a fresh water ornamental fish, Oscar (Astronotus ocellatus). Fish were fed with four isocaloric dietaries and 40%, 45%, 50% and 55% protein levels for 8 weeks. The highest and lowest weight gain were observed in fish fed with 40% and 50% dietary protein, respectively. Only, the significant difference of weight gain was observed between 40% dietary protein than other dietaries protein (P<0.05). The lowest and highest protein efficiency ratio were obtained in 55% and 50% dietary protein, respectively. But, there was not any significant difference of protein efficiency ratio between various dietaries protein (P>0.05). The lowest and highest specific growth rate were observed in 40% and 50% of dietary protein, respectively. The best feed conversation rate was obtained in fish that fed with 45% dietary protein. Results obtained from the feed conversation rate parameter of Oscar fish showed that with increasing the dietary protein from 40% to 45%, better feed conversation rate can be seen in fish, but, with further increase of dietary protein to the 50% and 55%, feed conversation rate parameter will increase.