Biology of the Spotted Scat (Scatophagus argus) in the Philippines

Abstract

The spotted scat (Scatophagus argus) is an herbivorous, euryhaline teleost widely distributed throughout the Indo-Pacific basin. This species is a valuable brackishwater aquarium fish and an important foodfish in parts of its range. Length-weight relationships were calculated based on data from 797 females and 252 males. The sexes can be differentiated by head shape. The largest fish captured was a 1.2-kg female. Reproductive maturation first occurred in females of approximately 150 g, corresponding to fish estimated to be 7-9 months of age. Males mature at a smaller size (-80 g). Fecundity was found to be directly proportional to fish size. Data on the monthly abundance of mature females and fry (which peaked markedly in August) suggest that monsoon rains (which began in June) trigger spawning in the spotted scat. Observations of spawning behavior and early juvenile development are also reported.