The food value of five clones of Haptophyceae,Coccolithus pelagicus, Dicrateria zhanjiangensis, Isochrysis galbana, Tahitian Isochrysis aff. galbana, and Pseudoisochrysis paradoxa were tested for larval Penaeus orientalis. The algae were semicontinuously cultured in 5,000ml carboys with 4,000ml of Guillard f/2 medium, under 2,000lux continuous light and under aeration. The algal density was up to 1×10^7cell/ml. Rearing experiments were conducted in round tanks with diameter of 45cm. Algal density was controlled to 1～10^5cell/ml in the course of the experiments. The larval density was 18 individual/100ml, water temperature 21-24℃, pH 7.5-7.7, sea water specific gravity, 1.019. The results showed that of the five clones used,Tahitian Isochrysis aff. galbana and Dicrateria zhanjiangensis proved to be thebesto It took 9-11 days for nauplius Ⅵ to develop into mysis I with survival rate of 73.5% and 73.4% respectively.
