Fig. 6. Acclimation induces gonadal maturity in males. The relative number of spermatogonia, spermatocytes and spermatids/sperm present in the testis were assessed in five experimental groups. Jul, fish captured in July; Accl.1, fish captured in July and acclimated for 30 days at 28°C (constant photoperiod and water conductivity); Sept, fish captured in September; Accl.2, Fish captured in September and acclimated for 30 days at 28°C (constant photoperiod and water conductivity); Nov, fish captured in November. Testes of males freshly captured in July have spermatogonia and spermatocytes. After acclimation (grey) the cell profile changed and resembled a mature male, presenting almost 40% of advanced germ cells (spermatids and sperm). The experiment was repeated with a group of fish collected in September, with similar results. White bars, spermatogonia; hatched bars, spermatocytes; black bars, spermatids and sperm.