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Summary

Ovaries of 1159 Trachinocephalus myops were examined, and six oocyte stages were histologically identified whereby each stage of ovary development was observed almost every month. The sex ratio was not different from 1 : 1 (P > 0.01). The weight-length relationship was estimated as BW = 0.0077FL3.1207 (r2 = 0.976, n = 2256). Monthly composition of the oocyte stages gonadosomatic index (GSI), and condition factor (CF) were examined. The spawning season had two peaks: February to April and August to October. Sizes at 50% maturity were estimated at 18.0 and 18.7 cm FL for females and males, respectively. Fecundity estimates ranged from 11 100 to 426 200 (mean: 178 600), based on an oocyte diameter >0.2 mm. Batch fecundity was estimated to range from 1724 to 120 951 (mean: 60 200), germinal vesicle migration and mature oocytes >0.8 mm in diameter were counted, and the relative fecundity was estimated to range from 346 to 3115 (mean: 1087). The results suggest that reproductive activity occurred throughout the year, suitable for the highly variable environments utilized by this species.