Acute toxicity of non-ionized ammonia on tambacu (Colossoma macropomum x Piaractus mesopotamicus)

Resumo

Ammonia is a toxic compound to aquatic organisms and at high concentrations in water, it can cause various
changes in the animal. Therefore, it becomes important to determine the tolerance of farmed aquatic animals for that substance.
Thus, the aim of this study was to determine the mean lethal concentration (LC50-96 h) of un-ionized ammonia (NH3
) in tambacu
fingerlings (Colossoma macropomum x Piaractus mesopotamicus) in acute toxicity test. The fingerlings were exposed to
ammonia at concentrations of: 0.09 (control); 0.54; 1.23; 2.52; 3.44 and 3.66 mg L-1 NH3
, which were obtained from the
application of NH4
Cl. The test lasted 96 hours and mortalities were recorded over that period. The LC50 was determined by
the Trimmed Spearman Karber statistical method. The LC50-96 h of non-ionized ammonia (NH3
) for fingerlings of the tambacu
hybrid was 1.63 mg L-1
.