Submitted to: NWAC (National Warmwater Aquaculture Center) Aquaculture Newsletter
Publication Type: Popular publication
Publication Acceptance Date: 11/1/2003
Publication Date: 11/30/2003
Citation: Mischke, C.C., Li, M., Wise, D.J., Zimba, P.V. 2003. Zooplankton nutritional value: Nursery pond fertilization effects. NWAC (National Warmwater Aquaculture Center) Aquaculture Newsletter 5(2):8-9, 12. Interpretive Summary: Growth of catfish fry on natural zooplankton is largely unknown. Natural food resources were analyzed for chemical (nutritional) content to determine if the food quality was sufficient to support catfish growth. The catfish nutritional requirements were met by zooplankton in all cases except for two non-essential fatty acids. These results suggest that an altered management strategy of not feeding juvenile fry catfish expensive prepared feeds during the first 2-3 weeks of growth would be practical.
Technical Abstract: Little information is available on the utilization of natural productivity (i.e. zooplankton) by catfish fry. Although fry and fingerlings survive on prepared diets, many nutrients acquired by fry in ponds are most likely derived from natural food consumption. Experiments were conducted to answer the following questions: 1)What is the nutritional value of zooplankton, and 2)Is zooplankton nutritional value affected by fertilization? Samples of zooplankton from each pond were analyzed for proximate nutrients, minerals, amino acids, fatty acids, and vitamins. Fertilized and non-fertilized pond zooplankton were similar in nutritional value; only two fatty acids (C16:0 and C20:4 n-6) were significantly (P < 0.05) different between fertilized and non-fertilized ponds. The zooplankton in this study met or exceeded all nutritional requirements of catfish fry; fertilization of these ponds did not affect zooplankton nutritional value with the exception of pantothenic acid and vitamin B6, which were below the catfish fingerling requirement in zooplankton from non-fertilized ponds. If fertilization practices maintain large numbers of zooplankton, all fry nutritional requirements should be met through the natural biota. Additionally, it may be beneficial to offer zooplankton to fry while still in the hatchery.