The effect of fluoride on fertilized eggs of a freshwater fish, Catla catla (Hamilton)

The eggs of Catla catla were exposed to 2 fluoride media, (1) effluent dilutions containing 1.86, 3.21, 7.12, 9.56, and 16.23 ppm fluoride, and (2) fluoride (NaF) solutions containing 1.86, 3.56, 7.34, 10.01, and 16.68 ppm fluoride. The eggs exposed to 1.86 ppm fluoride (in both media) hatched at the end of 6 h, while in rest of the fluoride concentrations hatching was delayed by 1-2 h. The eggs showed decreases in water and protein and increase in fluoride contents. Toxicity of fluoride to eggs was more related to the availability of fluoride ions, than to the total fluoride in the media.