Increasing demand for tilapia fingerlings is based on their wide acceptance as major source of animal protin in many Asian countries. In the Philippines alone, millions of fingerlings are needed for stocking in pens and cages. To meet this demand, the existing backyard hatcheries in the country will have to expand and improve their larval-rearing techniques. Providing fry with the most suitable algal food would enhance growth and survival, thereby reducing costs. At a workshop on induced fish breeding in Southeast Asia (IDRC 1981), the natural food requirement was identified as one of the problem areas inlarval rearing. Reports from different countries showed that animal protein, mostly Moina and Daplnia, has commonly been used as larval food for freshwater species. On the other hand, about 40 algal species have been tested for nursery rearing of juvenile bivalves in other countries (De Pauw 1981). The food valeu of algae differed even among related species within the same class, family, or genus. THis paper describes which among five species representing four algal divisions is most acceptable to tilapia fry based on their growth and survival rates as well as assimilation rates of C^{14- labeled algae.}