Clinical and Pathological study of long term bath of zinc sulfate on cutaneous healing in common carp (Cyprinus carpio)

Cutaneous lesions in fishes due to viral, bacterial, parasitic, mechanical and chemical agents are very common, leading to severe infection and high mortality. The aim of this research was to investigate the effect of long term bath of zinc sulfate (15 and 23 ppm), healing of cutaneous lesions caused by surgical incision in carps. In this study, 210 carps were disinfected by 3% salt solution for 15 minutes. In each fish, an incision of 1.5 cm long and 2 mm deep was made on the left dorsal side. The fishes were then randomly divided into 3 groups, 70 fishes in each group. One group served as the control, and the other two groups were considered as the test groups which treated with 15 and 23 ppm of zinc sulfate respectively. During the study, at days 1, 2, 3, 5, 7, 10, 14 and 21, 7 fishes were randomly selected and tissue samples were prepared from incision site. Histopathological examination revealed that regeneration process of epithelial tissue was started at day 2 and was completed at day 7 in all fishes. However the healing process in group 2, particularly the formation granulation tissue, was started and completed earlier than group 1 and the control group. According to the results of clinical assessment and histopathology, it is concluded that long term bath of zinc sulfate has positive effects on fibroplasia during the healing process of cutaneous lesions.