Effect of water-born colloidal silver nanoparticles and silver nitrate on gill histopathology of Rainbow catfish, Pangasianodon hypophthalmus

Nowadays, silver nanoparticles have very important application in different industries mainly because of the antimicrobial activity. The purpose of this investigation was to evaluate the possible effects of silver nanoparticles in comparison with the silver ions (as silver nitrate) on some histopathological alterations in gill of rainbow catfish. Eighty-five individual of rainbow Catfish (12 ±0/26 g and 10/7 ± 0/46 cm) were randomly divided into 5 glass tanks (each 100 L) each one was considered as a treatment. The experiment was conducted in 10 days and consisted of five treatments as follows: 1 μg / L silver nanoparticles, 1 μg/L silver nitrate, 20 μg/L silver nanoparticles, 20 μg/L silver nitrate and the control group. At the end of the experiment, the gill tissues were prepared for histological studies. Hyperplasia of gill filaments and gill secondary lamella as well as shortening and looping structures of the secondary lamellae were observed in the gill tissues. Quantitative analysis was done using organ index (Iorg). The Iorg was in the range of 1.33-11.66 were the highest and lowed tissue alternations were observed in the fish which belonged to the highest dose of silver nitrate and control group respectively. The results showed that although silver nanoparticles and silver nitrate have significant adverse effects on gill tissues of rainbow catfish, silver nitrate caused much more structure alterations when compared to similar dose of silver nanoparticle (P<0.05).