A Preliminary Study on the Dietary Protein Requirement of Larval Japanese Flounder Paralichthys olivaceus

Sungchul C. Bai, Young-Taeg Cha, Xiaojie Wang-2001

North American Journal of Aquaculture, 63(2): 92-98

Abstract:
This experiment was conducted to estimate the dietary protein requirement of larval Japanese flounder Paralichthys olivaceus (also known as the olive flounder) and to examine the effects of a commercial diet and three experimentally developed microparticulate diets (MPDs) on their growth and body composition. Larvae were fed four MPDs for 75 d beginning 8 d after hatching (DAH); fish in these experimental diets were also concurrently fed live feeds until 45 DAH, as is the normal procedure in commercial hatcheries. One MPD was a commercial diet (CD) of marine fish in which crude protein ranged from 55.8% to 61.2% (dry weight basis; varied with pellet size); the three laboratory-prepared diets based on Japanese flounder muscle contained either 40% (D₄₀), 50% (D₅₀), or 60% (D₆₀) crude protein.

At 83 DAH, body weights and lengths of fish fed diet D₆₀ were not significantly different from those fed diet CD. Fish fed diet CD had significantly greater body weights and lengths than those fed diets D₄₀ and D₅₀. Percent survival and whole-body compositions of moisture, protein, and ash were not influenced by dietary treatments during the 75-d experimental period. Although whole-body fatty acid composition generally was not significantly different among diet treatments, fish fed diet CD had significantly greater α -linolenic acid (C18:3ω3) by the end of the experiment. The results suggest that the optimum dietary protein level for maximum growth and survival of Japanese flounder larvae should be 60% or more. The experimentally developed MPD therefore shows potential utility, and additional nutritional research with Japanese flounder larvae is warranted.

(Department of Aquaculture, Pukyong National University, Pusan 608-737, Korea)

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