D. ALLEN DAVIS AND CONNIE R. ARNOLD, The University of Texas at Austin, Marine Science Institute, 750 Channelview Drive, Port Aransas, Texas 78373, USA

Atlantic Croaker Micropogon undulatus belongs to the family Sciaenidae. This fish is abundant in the bay systems year-round and is heavily utilized as both a bait fish and as an excellent food fish. The development of culture techniques for this species would allow an alternative to the harvesting of wild stocks, diversity aquaculture and expand our understanding of this species. However, to successfully culture a new species, considerable information must be obtained on major life stages, environmental requirements and nutritional needs. In response to commercial request, this research sought to initiate the development of practical diet formulations for fingerling growout and to evaluate the response of this species to controlled culture conditions. Eggs were hatched and the larvae reared under controlled culture conditions similar to those used for red drum. After 78 days of culture fish were transferred to a research system and conditioned to the culture conditions. A series of eight practical diets were formulated to contain 45, 40, 35 and 30% protein with varying energy contents. Each test diet was offered to four replicate groups of fish (10 fish/tank) having a mean initial weight of 3.8 g. The fish were maintained in a semi-closed recirculating system over a 7 week growth trial. Temperature and salinity of the culture water was maintained at 28 C and 28 ppt. At the conclusion of the feeding trial, final weights of fish maintained on the test diets ranged from 19.2 g (410% weight gain) to 12.0 g (210 % weight gain) with 100% survival for all dietary treatments. Weight gain and estimated feed conversion efficiencies significantly increased with protein content of the diet. Weight gain of fish maintained on the 45% protein diet decreased, but not significantly, as the lipid content of the diet was increased from 8 to 12 or 16%. Estimated feed conversion efficiencies for fish maintained on the 45% protein diet with 8% lipid were significantly higher than that of fish maintained on the 45% protein diet containing 16% lipid. Based on the observed results, the Atlantic croaker adjusts well to controlled culture conditions and responds well to laboratory handling. The observed results would indicate that this fish grows best on a high protein diet with moderate lipid levels.