The Acute Effects of Un-ionized Ammonia on Zebrafish (Danio rerio)

Zebrafish is a commonly used species in toxicology studies investigations such as molecular genetics, histopathology and developmental biology. A toxicity test was conducted to investigate the effects of toxic ammonia (NH3) in relation to time and concentration by establishing a measurable endpoints for chemical exposure and monitoring the biological responses on zebrafish exposed to high levels of toxic ammonia concentration using ammonium chloride (NH4Cl) as E1: 17.21 mg/l, E2: 24.51 mg/l, E3: 25.81 mg/l, E4: 32.11 mg/l and E5: 38.91 mg/l NH3-N at 24 hr, 48 hrs and 72 hrs periods. Fish exposed to the high levels of toxic ammonia exhibited hematological, histopathological and molecular alterations to the gills, liver and kidney at all exposure periods 24 hrs, 48 hrs and 72 hrs. The interrelation between the hematological, histopathological and gene expression have proven to be time and dose dependent having a linear relation under the influence of high levels of toxic ammonia exposure. Such hematological and histopathological changes observed in the gills, liver and kidney of zebrafish in the present study indicates that the fish were responding to the direct effects of the toxic ammonia and secondary effects caused by stress.