Biotechnology and aquaculture of rotifers

Biotechnology can be defined as any technology that involves living organis ms or their derivatives. In applying this definition to rotifers, we focus on their contribution in culturing of early larval stages of marine fish. A fter almost four decades of marine fish culture in captivity, the success o f this worldwide industry is still quite dependent on mass culture of the s pecies Brachionus plicatilis and B. rotundiformis. In mass culture, the rot ifers are continuously driven to reproduce at high rates, in relatively ext reme environmental conditions of high population density and high loads of organic matter. Therefore, the success of mass cultures and future improvem ents in these systems relies on a close interaction between basic and appli ed studies of rotifers. In the present review, we will attempt to analyze w hy rotifers are suitable for early life stages of fish and to describe, in general, methodologies that have been devised for reliable supply of rotife rs in large quantities. Problems associated with rotifer production, nutrit ional quality and effect on fish health and nutrition, will be discussed. R esearch on B. plicatilis and B. rotundiformis has increased enormously duri ng the past three decades and these two species are the best-studied rotife rs so far. While much of the research on these species is directed or devot ed to the needs of aquaculture industry, they are also used as models for a ddressing basic biological questions, due to the relative ease of culture a nd their availability. Studies on feeding, pheromones, speciation in rotife rs, the occurrence and putative hormones involved in sexual and asexual rep roduction and production of resting eggs, are few examples of such studies. Rotifers will probably maintain their role as food organism for fish larva e, in spite of attempts to replace them with more accessible formulated foo d. Development of new culture methods that will improve the nutritional qua lity and production efficiency of rotifers may result in more diversified a nd flexible tasks for these organisms in aquaculture.