It can get really, really high. Basically, ammonia will continue to rise if there is a source (fish or decaying matter) until the bacteria can start consuming. Until the bacteria population reaches a certain size, ammonia just keeps rising, then suddenly starts dropping. Do you have any nitrites yet?
Different animals have different tolerances for wastes. Many detrivore snails can put up with pretty high levels of ammonia, but keel over if exposed to a sudden change in pH.
Different animals have different tolerances for wastes. Many detrivore snails can put up with pretty high levels of ammonia, but keel over if exposed to a sudden change in pH.