Evaluation of decapsulated Artemia cysts in hatchery diets for channel catfish Ictalurus punctatus fry and effects on subsequent fingerling production

Two 10-d hatchery growth trials were conducted to determine if differences in growth, body composition, and survival existed among catfish fry Ictalur us punctatus fed a diet of 100% catfish-starter (CS) or CS in combination w ith decapsulated Artemia cysts (DAC) at 25%, 50%, or 75% of diet weight. A 120-d production trial was undertaken immediately following the first hatch ery trial to evaluate the effects of diet on production characteristics (su rvival, length, weight, feed conversion ratio, and total yield) of fingerli ng catfish produced from hatchery-raised fry. Fry fed diets containing DAC weighed 61-98% more (P < 0.05) than fry fed only CS. The size differential of DAC-fed fry was maintained through 120 d of growth in simulated nursery ponds (0.001-ha earthen-bottom pools). The increased growth of fry fed DAC might have been related to differences in dietary lipid content, amino acid composition, or digestibility of CS and DAC. Body weights of fingerlings p roduced under simulated production conditions from fry fed hatchery diets c ontaining 50% and 75% DAC were 17% and 25% higher, respectively, 130 d post -hatch, than fingerlings produced from fry fed only CS. In addition, the to tal yield of fingerlings produced from fry fed 75% DAC was 17% greater that that of fingerlings produced from fry fed only CS. The increased performan ce of fingerlings produced from DAC-fed fry could have resulted from their larger size at stocking, since larger fry might be capable of capturing nat ural food organisms and ingesting prepared diets more effectively than smal ler fish. CS-DAC diet combinations could be used to increase weight gain of hatchery-raised fry if the cost-benefit ratio of adding DAC to the standar d hatchery diet warrants its use.