Toxicity of formaldehyde on african catfish (Clarias gariepinus)

Abstract

The aquaculture activity is widely use formaldehyde (37% in formalin) to control ectoparasitic diseases. The African catfish (Clarias gariepinus) is one of commercial freshwater fish that been rear widely. Thus, a toxicity test was carried out to determine the safety level and other effect of formaldehyde on organism tissues and organs such as gills. The semi renewal toxicity test was used as formaldehyde has high evaporation rate. From the test that has been conducted, the 96-hours LC50 value for formaldehyde on African catfish ( Clarias gariepinus) is I 6.433ppm. Formaldehyde also capable in reduce DO level, and based on the readings DO level was decrease rapidly towards the increase of formaldehyde concentration. Other water parameter however did not shows significant relation. For the gills observation, it supposed to use SEM. However, due to technical problems the method was changed and the observation was only made through Motil Light Compound Microscope. Even thought the sample fixation method and sample condition not suitable for the microscope observation, still some changes on the gills can be observed where some part of the gills become decay when exposed to formaldehyde longer. Based on this study, the estimated safe concentration of formaldehyde is 0.1 of the LC50 value which is 1.6433ppm. However, more studies are needed to confirm it.