Fig. 4 in Ecology and life history of an Amazon floodplain cichlid: the discus fish Symphysodon (Perciformes: Cichlidae)

Fig. 4. (right column) Testes and ovaries of Symphysodon haraldi at advancing stages of gonadal development. Photographs are from freshly sacrificed and dissected specimens, with the gonads outlined for clarity. The following modified version of Nikolsky's scale of reproductive maturity was utilized: 0. (immature): gonads thin and transparent; sex determination not possible (not illustrated). 1. (early development or resting): testes thin and translucent; ovaries thin and translucent-pink with transparent eggs. 2. (maturing): testes translucent white; ovaries enlarged with white eggs. 3. (mature): testes thick and white; ovaries enlarged with largest eggs yellow. 4. (pre-spawning): testes swollen and sperm-positor everted; ovaries swollen with largest eggs orange, swollen and approximately 1.4 mm in diameter, ovipositor everted. 5. (spent): testes flaccid; ovaries flac- cid with scattered eggs of various size classes (not illustrated).