Toxicological Effects of Herbicide (miafuron) on African Catfish (clarias Gariepinus) Embryo Development and Viability

This research was carried out to determine the toxicological effects of miafuron herbicide on African Catfish (Clarias gariepinus) embryo development and viability. Embryo were obtained through artificial breeding using five (5) ripe brooders of Clarias gariepinus, of mean weight of 1.4kg and mean length of 32cm, 2 females and 3 males. Herbicide miafuron was obtained from Gidan gona in Mubi main market. Stock solution of 40μg/ml, 30μg/ml, 20 μg/ml, 10μg/ml, 1μg/ml and 00 μg/ml was produce for the research. Static bioassay was used using five treatments and three replications. Each treatment and replication was stocked with 100 embryos to determine the LD50 (concentration at which 50% will die) of the embryo and larvae exposed to different concentration of miafuron. Analysis of health of the embryos, extent of development, and the formation of apparent abnormalities were done to examine the physical deformities caused by the herbicide to embryo and larvae at various concentrations. Results from the research indicate that all concentration of miafuron tested, except for control, led to some form of toxicity, cardiac dysfunction, or other developmental error. Exposure of Claria gariepinus embryos to high concentrations of miafuron resulted in some embryos exhibiting cardiac dysfunction. However, due to variation in the results at different concentrations, the LD50 (lethal dose 50%) of the herbicide was found from 200 μg/ml. However, at concentrations slightly higher than the LD50, embryos exhibited a general toxicity that led to 100% mortality. Different concentration treatment led to variability in mortality at different stages of development. However, within the suspected LD50, mecoprop treated embryos exhibited cardiac dysfunction, as well as a host of other abnormalities: shortened body axis, micropthalmia, curved spine, tail malformation, lack of motility, and abdominal edema. At a higher range of concentrations, it resulted in cardiac dysfunction as well as defective pigment cell alignment, shortened body axis, micropthalmia, tail malformation, lack of motility, and abdominal edema. The results of this study provide evidence that miafuron herbicide at low concentration, appears to be safe for Clarias gariepinus embryonic development and survival. However, at higher concentration of 40μg/ml, this herbicide has teratogenic effects that need to be explored further.