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.