Effect of dietary fish oil replacement with palm oil on growth performance, hematology and liver anti-oxidative enzymes of juvenile Japanese flounder Paralichthys olivaceus (Temminck & Schlegel, 1846)

A 60-day feeding trial was conducted to evaluate the effects of dietary palm oil supplements on growth performances, hematology, liver anti-oxidative enzymes and air exposure resistance of Japanese flounder, Paralichthys olivaceus (initial weights 2.56 +/- 0.01g). Five diets were tested wherein the dietary fish oil was replaced by palm oil at: 0% (Control), 20% (20%), 40% (40%), 50% (50%) and 60% (60%). After the feeding trial, the 20% dietary palm oil was shown to provide similar growth rates and feed efficiency with no negative effects compared to the control group (P>0.05). Significantly lower growth rates and feed utilization were found in fish fed higher than 40% palm oil in the diet (P<0.05). Except for total serum protein, the blood parameters, liver anti-oxidative enzymes, stress resistance and proximate compositions of Japanese flounder were not altered, even with dietary palm oil up to 60% of the lipid source (P>0.05). According to the present results, palm oil is a valuable lipid source substitute in Japanese flounder diets; around 20-40% fish oil can be replaced with palm oil with no negative effects.