Levels above 1.0ppm of ammonia or nitrite could kill fish, or make hardy fish ill. ... A few days without food is much better than trying to feed lethargic fish and making the problem worse. If the fish are looking worse for wear, prepare for a water change.

What ppm of ammonia is safe for fish?

The only safe level of ammonia is 0 parts per million (ppm). Even concentrations of just 2 ppm can cause fish to die in your tank.

Is 0.50 ppm ammonia bad?

Ammonia is a toxic substance that is one of the major causes of fish illness and death. Ammonia levels should always be 0.5 parts per million or less.