Histopathological effects of waterborne copper nanoparticles on the gill of rainbow trout (Oncorhynchus mykiss) fry

In the present study, totally 300 rainbow trout fry with an initial weight of 6.44 ± 0.37g (Mean ± SE) were randomly allocated to 15 fiberglass tanks (with 45 L volume and20 L water volume) at 5 different Cu-NPs treatments with 3 replicates. Treatmentswere the control (no added Cu-NPs), 5, 10, 20 and 40 μg/l Cu-NPs (mean primaryparticle size of 2-6 nm) in a semi-static waterborne exposure regime. The fish gillwere sampled at day 10 and samples were dehydrated by routine methods andembedded in paraffin wax. They were sectioned by microtome and stained with H &E. All treatments caused organ injuries including: necrosis (5 and 40 μg/l Cu-NPstreatments); Hydropic degeneration (10 and 20 μg/l Cu-NPs treatments); hyperplasiaand fusion of secondary lamellae (10 and 40 μg/l Cu-NPs treatments); epitheliumlifted away from the basement membrane (10 μg/l Cu-NPs treatment); shortening ofsecondary lamellae (10, 20 and 40 μg/l Cu-NPs treatments); shortening of gillprimary lamella and loss of secondary lamellae (20 and 40 μg/l Cu-NPs treatments)and congestion (20 μg/l Cu-NPs treatment).

Keywords:

Copper , Nanoparticles , Gill , Rainbow trout , Fry