Comparison of taurine biosynthesis ability between juveniles of Japanese flounder and common carp

This study was conducted to investigate taurine deficiency and the ability of taurine biosynthesis in both juvenile Japanese flounder (JF) and juvenile common carp (CC) in vivo using low taurine level diets. Three different taurine level diets were prepared by the supplementation of taurine to the basal composition (JF--0, 0.5 and 1.5% in JF; CC--0, 1, 3% in CC). The final average body weight and feed efficiency of JF fed the JF - 1.5% was significantly higher than those of fish fed on the JF--0%. On the other hand, no significant difference was observed in CC fed with CC--0, 1, and 3% diets. The taurine retention rate was negative in the case of JF-fed with the taurine-free supplement (JF--0%). On the other hand, the taurine retention rate was about 280% in the case of CC-fed with the taurine-free supplement (CC--0%). These findings indicate that while taurine is essential for growth of JF, it is not essential for the growth of CC.