Identification of a calcium-critical period during channel catfish embryo development
2004
Small, B.C. | Wolters, W.R. | Bates, T.D.
The embryonic development of channel catfish Ictalurus punctatus was studied by collecting eggs from spawning adults and placing them in tanks that were supplied with calcium carbonate at high (100 mg/litre) or low (<10 mg/litre) concentrations. Every 24, the calcium-supplemented water was turned off and replaced by low-calcium water. After another 24 h, the high-calcium water was restored and the low-calcium water was supplied to the next tanks, until hatching occurred on the 6th day. The total number of fry were counted in order to calculate hatching success. It was shown that hatching success was significantly affected by water calcium hardness. The first 24 h of embryonic development was the only calcium-critical period. Hatching success was 72% lower in the eggs supplied with low-calcium water during the first 24 h compared to the controls, which received calcium-supplemented water throughout the whole period. Hatching success averaged 60.8±2.2% during the remaining 24 h of development and was similar to the controls (68.7±3.4%). These results provide evidence that calcium supplementation is needed for managing an optimal hatchery environment for channel catfish.
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