Table 2 Characteristic of gonadal development stages for male and female

Stage I (Immature)

Testes are very small with grey color

Ovaries are small and transparent with yellowish-orange color

Stage II (Resting)

Testes become white, like ribbon

Oocytes in ovaries are still invisible in gonad ovarian wall

Stage III (Developing)

Testes are white and settle approximately half-length of body cavity

Ovaries are larger than stage II and oocytes are visible in gonad ovarian wall

Stage IV (Maturing)

No milt appears and testes occupy more than half-length of body cavity

The ovaries are larger than stage III, creamy orange in color; large oocytes are present in ovarian wall

Stage V (Mature)

Milt appears and 1/3 gonads fill to ventral cavity of testes

Ovaries are massive, yellowish color and occupy approximately 1/2 to 2/3 of body cavity

Stage VI (Spawning)

Milt excludes from testes firm strain to abdominal part

The extensive capillaries of ovary are clearly visible in ovarian wall

Stage VII (Spent)

Testes are smaller than stage V and VI with frail testes not fully empty

Ovaries are smaller than stage V and VI but flaccid and reddish color; some massive oocytes still appear in ovarian wall

Stage VIII (Recovering)

Testes are placid and small with reddish and brown color

Ovaries are small, flaccid and red-dark in color