Aspects of the biology of three fish species, Apogon nigripinnis, Leptoscarus vaigiensis and Siganus sutor, associated with seagrass beds (Thalassodendron ciliatum / Cymodocea serrulata and Thalassia hemprichii / Halodule wrightii) were studied at Inhaca Island (Mozambique). Stomach contents analysis showed that both L. vaigiensis and S. sutor are herbivorous and A. nigripinnis is carnivorous. A. nigripinnis spawns between October and March, and S. sutor between September and February. In the case of L. vaigiensis, mature individuals were found during almost all times of the year. Monthly occurrences from day and night sampling are described for these species in the T. ciliatum / C. serrulata seagrass association.