DHA enrichment of rotifers: A simple two-step culture using the unicellular algae Chlorella regularis and Isochrysis galbana

The ω3 highly unsaturated fatty acids (ω3 HUFAs) are important diet components for improving survival and growth in the early developmental stages of fish and prawns. Although a marine unicellular alga, Isochrysis galbana, contains large amounts of docosahexaenoic acid (DHA) and may enrich the rotifer, Brachionus plicatilis, population growth of rotifers fed on this alga alone was slow. Population growth of rotifers fed on the freshwater alga, Chlorella regularis, was much faster, but no DHA enrichment was observed. We first cultured rotifers using C. regularis for seven days, and added I. galbana one day before harvest. Rotifers cultured using this two-step system were enriched in DHA (2.2 mg/g dry weight) and EPA (3.3 mg/g dry weight).