ANTIFERTILITY ACTIVITY OF NONI (Morinda lucida) LEAF MEAL ON NILE TILAPIA (Oreochromis niloticus)

Tilapias are tropical aquaculture fish species and are yet to reach their full potential because of the problems of precocious maturity and uncontrolled reproduction, which often result in the overpopulation of production ponds with young or stunted fish. There is need to control unwanted/undesirable tilapia recruitment in ponds using natural reproductive inhibitory agents in ethnobotanicals (plants) because they are less expensive and constitutes appropriate technology in developing countries. Morinda lucida leaf meal was added to a basal diet (350g crude protein, 18.5MJ GE/kg diet) and fed at low dose (5 g/kg/day) or high dose (10 g/kg/day) to male or female Oreochromis niloticus for 60 days; to evaluate effects on reproduction traits and gonad histology.

There were no differences (P>0.05) in growth and feed conversion indices. Permanent sterility was induced in tilapias in the high dose treatment, while sterility in the low dose treatment was reversible, with no significant loss in fish weight (P>0.05). Both dose treatments decreased sperm motility, testis mass and sperm count, egg diameter; and inhibited gonadal development. Gonadal histology showed swollen testes nuclei in low dose treatment and disintegrated cells in high dose treatment; and varying degrees of disintegration of follicle cells and atrophy of ovarian nuclei in high dose treatment. The severity of cell destruction and vacuolation showed that antifertility activity was dose dependent. Reproduction traits, gonado-somatic index (GSI) as well as gonadal development and histology in O. niloticus fed high doses revealed that Morinda leaves were effective as antifertility agents, representing an appropriate technology that is easily adopted by resource-limited African fish farmers, as effective anti-fertility agents for farm-raised tilapias and to control prolific breeding which cause stunted tilapias.