Ammonia toxicity to fishes. effect of pH [hydrogen ion concentration] on the toxicity of the un-ionized ammonia species

Data on the toxicity of ammonia to rainbow trout and to fathead minnows from two series of 96-H flow through toxicity tests in which ph is controlled within the range 6.5-9.0 are presented. The toxicity of ammonia in terms of nh3 increases at lower ph values. Water Quality criteria should be revised to consider the ph dependence of the toxicity of ammonia.