Gonadosomatic Index, Oocyte Development and Fecundity of the Snakehead Fish (Channa striata) in Natural River of Mae La, Singburi Province, Thailand.

Abstract

Reproductive cycle of snakehead fish (Channa striata) is necessary to inform management plans of the natural fish. This work aimed to study the gonadosomatic index (GSI), oocyte development and fecundity of C. striata in the Mae La River, Singburi province, Thailand from November, 2017-October, 2018. GSI was calculated from gonadal weight and body weight. Ovarian sections derived from standard histological methods were used to evaluate oocyte development, respectively. Fecundity was measured using the gravimetric method and the relationships of fecundity-total length, fecundity-body weight and fecundity-ovarian weight were evaluated. The highest average GSI values for females and males were found in July (6.15±0.20 and 0.14±0.12, respectively). Ovarian histology revealed 4 stages of ovarian development: (1) immature, (2) maturing, (3) mature and (4) spent. Stages 1, 2, 3 and 4 were observed for 11, 10, 6 and 2 months, respectively. The highest percentages of immature, mature and spent oocytes were found in October (93.33%), July (89.56%) and August (33.33%), respectively. Fecundity ranged from 4,160-46,890. Fecundity varied depending on total length, body weight and ovarian weight, with correlation coefficients (R) of 0.986, 0.960 and 0.989, respectively. Oocyte maturation period of C. striata occurs from April to August. The highest gonads development was in July. Fecundity exhibited linear relationships with body length, body weight and ovarian weight.