This study is based on the analysis of macroscopic anatomy and histological structure of 452 ovaries from females of Cathorops spixii caught in the "Pai Matos" islands (Cananéia-Iguape lagoonal-estuarine region - 24°59'42"S 47°54'27"W), São Paulo, Brazil. Six phases of oocyte development are considered, based on cytological characteristics of the germinative cells during the maturation process, and seven ovarian maturity stages, determined by histological structure of ovaries and by the occurrence and relative frequency of the six oocyte phases: "A"(immature), "Bi"(initial maturation), "Bf'(advanced maturation), "Ci"(partially mature), "Cf'(mature), "D"(spent) and "R"(recuperation). The presence of a single patch of oocytes clustered during the spawn by an acellular adhesive substance, suggests total spawning, and the oocyte development is classified as synchronic in groups. The examined ovarian macroscopic anatomy and histological structure are characteristic of the cistovarian type.
Marine catfish; Fish reproduction; Gonads; Histology; Cathorops spixii; Reproductive cycle