ARS | Publication request: The effect of calcium hardness on hatching success of channel catfish Ictalurus punctatus x blue catfish I furcatus hybrid catfish eggs

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 22, 2011
Publication Date: June 13, 2012
Citation: Chatakondi, N.G., Torrans, E.L. 2012. The effect of calcium hardness on hatching success of channel catfish Ictalurus punctatus x blue catfish I furcatus hybrid catfish eggs. North American Journal of Aquaculture. 74:306-309.

Interpretive Summary: Hybrid catfish have gained popularity among the catfish producers for their superior performance compared to the commonly raised channel catfish coupled with consistent and increased availability of hybrid fingerlings in commercial quantities. However inefficiencies in hybrid fry production stemming from inconsistencies in egg quality and sub-optimal hatching conditions have increased the cost of fingerling production to catfish producers. Hence, there is a need to optimized production protocols to improve the efficiency of hybrid embryo production in catfish hatcheries. Hatching trials were conducted to incubate fertilized hybrid catfish eggs at four levels of calcium hardness waters under controlled conditions to determine the optimal concentration of calcium hardness that yield the highest hatching success of hybrid eggs. Commercial hybrid catfish hatcheries maintain a wide range of calcium hardness (25 to 100 mg L-1) in hatching waters with varying levels of hatching success of hybrid embryos. Even though initial fertility in did not differ among the treatments, hatching success of hybrid embryos incubated at 75 mg L-1 of calcium hardness was higher than the other three treatments. A hardness level of 75 mg L-1 calcium hardness is recommended in hatching waters to hatch hybrid catfish eggs in hatcheries and sub-optimal levels of calcium levels as presently practiced in commercial hatcheries appear to reduce the hatchability and increased vulnerability to other hatchery conditions. Optimal hatching waters improve the hatching success of hybrid embryos and may contribute to lower the cost of producing hybrid fingerlings.

Technical Abstract: The present study was designed to determine the optimal level of calcium hardness in hatching waters to incubate channel catfish Ictalurus punctatus ' x blue catfish I. furcatus ' hybrid catfish eggs. Hatching success of hybrid catfish eggs was higher (p<0.05) at 75 mg L-1 of calcium hardness (CaCO3) in hatching waters compared to 25 or 50 mg L-1 of calcium hardness; however further increases in calcium concentration did not improve hatching success. A minimum water hardness of 75 mg L-1 of CaCO3 is recommended for incubating hybrid catfish eggs.