Comparison of three live foods and two dry diets for intensive culture of grass carp and bighead carp larvae

Grass carp ( Ctenopharyngodon idella) and bighead carp ( Hypophthalmichthys nobilis) larvae fed freshwater rotifers ( Brachionus rubens) were consistently longer and heavier at the end of the 3-week feeding trials than those fed the other foods tested. The final length of grass carp fed nematodes ( Panagrellus sp.) was the lowest of the live foods tested, however, the length of bighead carp fed Panagrellus was not significantly different from those fed brine shrimp nauplii Artemia salina. Growth of grass carp fed the two commercial dry diets (Ewos Larvstart and Fry Feed Kyowa A) was less than those fed the three live foods. Bighead carp grew well on the commercial diets, but results were somewhat inconsistent. Construction of a simple, inexpensive airlift sponge filter is described. This filter provided adequate water quality, resulting in excellent survival at densities as high as 57 individuals/l with no addition of freshwater. The airlift sponge filter has great potential for intensive larval rearing.