The effects of different stocking densities on the growth, feed conversion ratio and survival of two size groups of the tropical abalone Haliotis asinina were determined. Three culture trials were conducted in net cages installed in a sheltered cove, Guimaras Province, Philippines. Trials 1 and 2 were conducted using 15–20 mm abalone juveniles for 150 days, while trial 3 was conducted using 35–40 mm abalone for 180 days. The animals were fed sufficient amounts of the red alga, Gracilariopsis bailinae (=G. heteroclada), throughout the experiment. There was an inverse relationship between growth (length and weight) and stocking density. Feed conversion ratio was not influenced by density, but was observed to be higher for larger animals. Survival was not significantly affected by density. Net cages are appropriate for culture of H. asinina. This study showed that H. asinina can reach commercial size of about 60 mm in one year. It also showed that growth of H. asinina can be sustained on a single-species diet. An economic analysis will be important in choosing the best stocking density for commercial production.