Effects of Calcium and Magnesium Hardness of Incubation Waters on the Hatching Success of Hybrid Eggs of ♀ Channel Catfish, Ictalurus punctatus × ♂ Blue Catfish, Ictalurus furcatus

Abstract

AbstractHatching efficiency is generally lower in channel catfish, Ictalurus punctatus × blue catfish, Ictalurus furcatus, hybrid catfish hatcheries compared to hatcheries hatching pond‐spawned channel catfish eggs. Egg quality and hatching water hardness are known variables influencing the efficiency of hybrid catfish fry production in hatcheries. Previous research recommended that at least 60 mg/L hardness had to be contributed only by calcium to optimize the hatching success of hybrid catfish eggs. However, whether the effect of waterborne magnesium in hatching waters facilitates or impedes the hatching success of hybrid catfish is not known. Two trials were conducted to determine the effects of calcium alone or magnesium hardness, in combination with the hatching success of hybrid catfish eggs. Trial 1 showed that if the previously identified minimum hardness criterion of 60 mg/L was met by calcium in the hatching waters, added magnesium had no effect on the hatching success of hybrid catfish eggs. Trial 2 showed that the previously identified minimum hardness of 60 mg/L can be met by either calcium alone or magnesium replacing up to 50% of the total hardness in the hatchery waters for optimal hatching success of hybrid catfish eggs. Calcium provides a specific requirement during embryonic development of catfish. The results from this study can be used to design treatment processes for hatchery water supplies to improve efficiency of hybrid catfish fry production in hatcheries.