Sublethal Toxicity of Formaldehyde in Common Carp (Cyprinus Carpio L., 1758)

Abstract

Formaldehyde (FA) is widely used as an antiparasitic agent and a general disinfectant in aquaculture and ornamental fish farming. This study was conducted to determine the chronic toxic effects of FA on carp. Cyprinus carpio fish with an average weight of 9.8±3.1 g and an average length of 7.3±0.7 cm was chronically exposed to FA using a semi-static test method. Sublethal concentrations were applied at 0, 20, 30, 40 mgL-1. The bioassay was continued at 23°C for 60 days. Fish samples were taken at 15, 30 and 60 days for analysis and evaluation. The fish were dissected and the liver and gills tissue were removed. Histological examinations were performed on the liver and gills tissue from fish. Glutathione (GSH) content, glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT) activity were also determined in the removed tissues. Morphological changes in the tissues were determined as proliferation in surface epithelial cells in the gill primer lamella, cleavage in the epithelial layer in the lamella of the seconder, and vacuolization in the liver. GST is significantly reduced in the liver at 40 mgL-1 at 15 days; SOD significantly decreased in the liver at 20, 30 mgL-1 in 15 days; CAT was significantly altered in the liver and gill at 30 mgL-1 in 15, and 60 days. With this study, it can be considered that FA has a slight toxic effect for the criteria examined in carp. Because FA is widely used in aquaculture, avoiding uncontrolled and unnecessary use will reduce the adverse biological effects that may occur. © 2017, Centenary University. All rights reserved.