Mass culture of the rotifer Brachionus plicatilis and its evaluation as a food for larval anchovies

Abstract

Growth rates of anchovy larvae, Engraulis mordax, reared for 19 days under constant environmental conditions on a diet of laboratory-cultured organisms, exceeded the growth rates of anchovies fed on a diet of wild plankton. The rotifer Brachionus plicatilis was found to be a nutritous food source when fed to the larvae in concentrations of 10 to 20/ml and in combination with the dinoflagellate Gymnodinium splendens (100/ml). Optimum conditions were determined for mass culture of the rotifer. A high food concentration was the most important parameter needed to assure a high yield of rotifers. Large volumes (464 I) of the unicellular flagellate Dunaliella sp. were cultured for feeding the rotifers. The rotifer culture technique described produces approximately 2.5×10⁶ organisms/day, providing a reliable food source for rearing studies. The lengths of B. plicatilis (without eggs) ranged between 99 and 281 μ, most rotifers being larger than 164 μ and less than 231 μ. Individuals weighed 0.16 μg and contained 8×10^-4 cal.