Calcium deprivation during channel catfish, Ictalurus punctatus X blue catfish, I. furcatus F1 hybrid catfish embryo development affects hatching success

Authors: Chatakondi, Nagaraj

Submitted to: Southeastern Association of Fish and Wildlife Agencies Conference
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2012
Publication Date: 3/31/2013
Citation: Chatakondi, N.G. 2013. Calcium deprivation during channel catfish, Ictalurus punctatus X blue catfish, I. furcatus F1 hybrid catfish embryo development affects hatching success. Southeastern Association of Fish and Wildlife Agencies Conference. 66:12-15.

Interpretive Summary: Hybrid catfish fry production in catfish hatcheries, where water supplies have low calcium concentrations and are of often supplemented with an external source of calcium. Nevertheless, failure of calcium pump or delivery system in hatcheries is not uncommon. Hatching trials were conducted, where three replicated baskets of fertilized hybrid catfish eggs were exposed to calcium deprived waters (0.4 mg/L calcium hardness) for twelve sequential 8-hour period from fertilization to hatch of hybrid catfish eggs. Fertilization rate of hybrid catfish eggs was not affected to exposure to calcium deficient waters. However, exposure of fertilized eggs to calcium deprived waters in any 8-hour period in the first 48 h post-fertilization reduced the hatching success of hybrid catfish eggs. The results of this study are important to commercial hybrid catfish hatcheries. This study suggests that 48 hour post-fertilization period appear to be the calcium-critical period in hybrid catfish embryo development. This study mimicked the commercial hatchery conditions, where calcium delivery system malfunctioned to result in the availability of calcium for a period of time until noticed. This study portrays significant losses of early embryonic stages of hybrid catfish exposed to calcium deficient waters. The study calls for developing procedures for vigilant monitoring of calcium hardness in hatching waters to reduce hatchery losses.

Technical Abstract: Channel x blue hybrid catfish are produced by fertilizing eggs from hormone-induced, strippable channel catfish (Ictalurus punctatus) females with sperm from blue catfish (I. furcatus). Many catfish hatchery supplies have low calcium concentrations and are supplemented with an external source of calcium. Nevertheless, failure of calcium pump or delivery system in commercial catfish hatcheries is not uncommon. This study examined twelve sequential 8-hour periods of calcium deficient waters from fertilization to hatch of hybrid catfish eggs. The periodical exposure to calcium deficient waters did not affect the fertilization of hybrid catfish eggs. However, any exposure period of hybrid catfish eggs to calcium deprived waters in the first 48 h post-fertilization reduced (P < 0.05) the hatching success of hybrid catfish eggs compared to the control group (not exposed to calcium deprived waters). This 48 hour post-fertilization period appears to be calcium-critical period in hybrid embryo development. Frequent monitoring of calcium hardness in hatchery waters is suggested to minimize losses in hybrid catfish fry production.