Gills of Juvenile Fish Piaractus mesopotamicus as Histological Biomarkers for Experimental Sub-lethal Contamination with the Organophosphorus Azodrin (R) 400

摘要

Piaractus mesopotamicus is a freshwater native fish from rivers of the Parana-Paraguay Basin and of the Pantanal region and has been used for repopulation programs in Brazil. Juvenile fishes were exposed to the sub-lethal dose of 1.08mg/L of the OP Azodrin (R) 400 containing 0.43 mu L/L of the active principle monocrotophos for 96 h. A frequent pathology in the gills at all times of exposure was epithelial detachment, from minimal until 24 h of exposure, to intense after 48 h of contamination. Deformed pillar cells in the respiratory lamellae leading to irregular blood spaces and blood congestion, as well as hyperplasia and lamellar fasion were observed. These histopathologies suggested that 48 h after T-0 was an important time when a reduction in the capability for gaseous exchange with consequent weakening of the fishes' condition could occur. This could impair growth and development of juveniles introduced in water bodies for repopulation programs.