A Beiranvand - Shahid Chamran University – Ahvaz- Iran
H Mavaly Zadeh
R Peyghan
B Mohamadian

Objective: Quaternary ammonium compounds (Quats) and formalin are widely used in disinfection and sanitation. They are effective against algae, bacteria and fungi. This product generally used to destroy, prevent the growth of, or otherwise exert a controlling effect on any harmful organism. The aim of this investigation was to determine the effect of these disinfectants on gill tissue of common carp. Method & Materials: 50 juvenile common carp were divided in to 5 groups of 10 fish each. First group considered as control‚ the 2nd group bathed in 1:2000 solution of formalin ‚the 3rd group in 1:2000 solution of Formalin + 0.5 ppm Benzalkonium chloride (BC)‚ in the 4rd group 1:2000 solution of Formalin +1ppm BC. In the fifth group 1:2000 solution of Formalin +2 ppm BC. After bath, mortality rate and survival time of fish in each groups were recorded. Samples from gills were taken and fixed in Formalin 10%. Histopathological sections were prepared by routine methods and stained. Results & Conclusion: The mortality rates in experimental groups were determined in 25ºC. In formalin, formalin+Benzalkounium chloride (0.5 ppm), formalin+Benzalkounium chloride (1ppm) and formalin+Benzalkounium chloride (2 ppm), the mortality rate were 40%, 70%, 100% and 100, respectively. In histopathological study, hyperemia and hemorrhage was the main sign of formalin in bath group. In combined Formalin and Benzalkonium chloride bath, cellular proliferation of gill lamellae, necrosis, atrophy and lamellar destruction were observed, that may be the main cause of hypoxia and death of the fish in this group.

Benzalkonium chloride, common carp, gill, formalin