The influence of copper sulphate pentahydrate (CuSO4•5H2O) on the embryo development in the guppies (Poecilia reticulata)

In the literature, there are no data on the effects of copper (Cu) on the development and birth defects of live-bearers freshwater fish embryos. The aim of this study was to investigate the influence of copper sulphate (CuSO4) pentahydrate on the development of embryos in the guppies (Poecilia reticulata). Guppies were exposed to concentration of 0.5, 1.0 and 1.5 mg/L of CuSO4 pentahydrate for 24 h. After 15 days, the female fish was euthanised and the embryos were dissected. No visible lesions were observed in the embryos of guppies exposed to 0.5 mg/L of CuSO4 pentahydrate. In the guppies exposed to 1.0 mg/L CuSO4 pentahydrate, the embryos showed visible abnormalities from blastodisc to middle- eyed stages of development. In the late (very late-eyed and mature embryo) stages embryos, the morphological abnormalities were not observed. The exposure to 1.5 mg/L of CuSO4 pentahydrate caused the death of guppies and their embryos during 24 h. In the light of these results, the 1.0 mg/L and higher dose of CuSO4 pentahydrate is not recommended for the treatment of guppies because this decreases the viability of guppies and causes morphological abnormalities and mortality in their embryos.