Submitted to: Aquaculture America Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 2007
Publication Date: February 9, 2008
Citation: Torrans, E.L., Bosworth, B.G., Ott, B.D. 2008. Effect of Dissolved Oxygen Concentration on Development and Hatching of Channel Catfish Ictalurus punctatus Eggs [Abstract]. In: Book of Abstracts. Aquaculture America, February 9-12, 2008, Lake Buena Vista, Florida. p. 274. Technical Abstract: Recommendations on required dissolved oxygen (DO) concentrations in channel catfish hatcheries vary widely. This study was conducted to determine effects of DO concentration on development and hatching success of channel catfish eggs. Five channel catfish spawns were collected from a pond at the Thad Cochran National Warmwater Aquaculture Center, Stoneville, Mississippi. Mean egg wet weight was determined on each spawn after counting a 10-20 g sample separated with a sodium sulfite solution. Each spawn was then split into two similar portions, and weighed to the nearest 0.1 g. The partial spawns were placed in hatchery baskets that were suspended in ten identical 185-L square fiberglass tanks. One portion of each spawn was assigned to the low oxygen treatment (with an average DO concentration of 5.81 ± 0.16 mg/L – 73% air saturation) and one to the high oxygen treatment (with an average DO concentration of 15.93 ± 0.28 mg/L – 199% air saturation). Water flow averaged 2.27 ± 0.12 L/min (one exchange every 81 min) and the temperature averaged 26.6 ± 0.01 C during the study, with no difference between treatments. The time hatching was over 95% complete was noted for each spawn (Table 1). Upon hatching, the fry in each tank were siphoned through a fine-mesh net, and weighed to the nearest 0.1 g. A sac fry sample was taken from each tank and counted to determine wet weight which was used to calculate survival to hatch. Eggs in the low oxygen treatment hatched 23.9 hours later than eggs in the high oxygen treatment, and had a survival to hatch of only 37.4%, compared to 74.8% for eggs in the high oxygen treatment. Although they were in incubation for nearly a day longer, sac fry that hatched in the low oxygen treatment were visibly less developed (less pigmentation) than sac fry from the high oxygen treatment. While DO concentrations in catfish hatcheries as low as 4-6 mg/L have been recommended, these results indicate that higher concentrations are necessary.