GROWTH AND FEED UTILIZATION OF STARRY FLOUNDER Platichthys stellatus  FED DEITS WITH GRADED LEVELS OF PROTEIN

Starry flounder is being cultured as a new candidate species, because olive flounder and rockfish occupy more than three quarters of marine cultured fish production in Korea. Although growth rate is slow, starry flounder is disease-resistant and grows under wide range of temperature. Furthermore, its farm-gate price demands higher than those of two main species. Nevertheless, very few nutritional research has been conducted, thus fish meal-based diet is being commercially produced for the fish. Therefore, an attempt to establish the optimum level of protein in diet was carried out.

A total of 360 fish with an average weight of 76.7 g was randomly distributed into each (150 L) of 18 tanks (20 fish/tank). Fish were fed one of six diets containing 30, 35, 40, 45, 50 and 55% protein to apparent satiation twice a day. Graded protein was prepared using a combination of casein and α-starch. Feeding trial lasted for 4 months during which water temperature varied from 15.6 to 25.0 ℃. Although daily feed intake (DFI, %) was not significantly different, fish group fed 55% protein showed a significantly higher (p<0.05) weight gain (WG) and specific growth rate (SGR) than other groups. However, feed efficiency (FE) was highest in fish fed 45% protein, although it was not significantly different among groups fed more than 35% protein. Higher protein efficiency ratio (PER) was found in fish fed lower protein diets. From the present results, it was concluded that optimal protein level in diets for starry flounder would be in the range of 45 to 55%.