Mucuna beans seed as fertility control agent on Nile tilapia (Oreochromis niloticus)

Matured male and female Nile tilapia (Oreochromis niloticus) were fed 5.9 and 11.8 g/kg/day of ground mucuna beans seed (Mucuna urens) as low and high dose treatment respectively to find out if the treatment could induce sterility. During the 30 days treatment period no spawning occurred in any of the treatments but there was spawning in the control experiment. There was no spawning after the treatments were discontinued; no spawning occurred even when previously treated fish were later stocked (mated) with untreated fish. Both low and high doses induced irreversible sterility in male and female Nile tilapia. Histological sections of the gonads showed that mucuna bean seed acted directly on the gonads to induce sterility by eroding and causing malfunctioning of the germ cells. The treatments combined clumping of cells, destruction of cell membrane, staining, and masking together with eroding of cells to achieve sterility. Eroding effect of the Mucuna treated feed was more pronounced in the high dose treatment where the numbers of cells were greatly reduced. Male and female gonads were similarly affected. The study reveals that mucuna bean seed could be used to induce permanent sterility in Nile tilapia though high doses could be toxic.