Abstract: This study investigates the toxic effect of wastewater effluents on the early developmental stages (eggs and larvae) of Heterobranchus bidorsalis. The wastewater effluents were collected from the portion where the waste flowed out through a concrete channel from students hostel. Six concentrations of the effluents (2%, 4%, 6%, 8% and 10%) and the control (0%) were used. There was a correlation between the various sewage effluent concentrations and sensitivities of the embryos. The higher concentrations of effluents, 8% and 10% were very toxic, less than 50% hatching success was achieved. The median mortality time (MT50) and total mortality time (MT100) decreased with increasing wastewater effluent concentration and were significantly difference (P < 0.05) in all the tested concentrations of wastewater effluents. The results of this study show that wastewater effluent had slight effect on egg fertilization, hatchability and survival of fish larvae.