Ammonia Poisoning in Aquarium Fish
Ammonia poisoning is undoubtedly one of the leading causes of death in aquarium fish. It is important to
know the causes and effects of ammonia toxicity so that the aquarist can recognize and take swift action.
Ammonia is always present in our aquaria. In a healthy, cycled tank nitrosomas bacteria oxidize the ammonia quickly.
Elevated ammonia levels occur when the levels of bacteria are insufficient to process the amount of ammonia produced.
Severely elevated ammonia can be due to a new tank, cleaning a filter with chlorinated water, treatment with
certain antibiotics, excess food, a dead fish going unnoticed.
Levels of ammonia as low as .25 Parts Per Million (PPM) can cause damage and distress, and ammonia levels of 1 PPM will cause damage,
even if the fish don't show any symptoms. Higher than 1 PPM or extended exposure to elevated levels cause
irreversible damage and shorten the life of the fish.
Ammonia toxicity starts at the gills. The fish start gasping or hovering at the surface and the gills will
Continued exposure irritates the skin. The fish will start flashing and flicking and may seem agitated. You
may notice a milky appearance to the fish because of increased slime production or the fish may get very dark.
At this point the gill tissue will start to die off and you may notice shreds of gill tissue. The gills may
look grey or pale.
Further exposure and the ammonia invade the entire system. The fish will stop eating and move less and less.
Eventually they will stay at the bottom. The fins may be burned away at this point.
As elevated ammonia continues, their tissues will be damaged. If you see red streaks or bloody places on their
body and fins, there is internal damage to internal organs and brain. If it goes on long enough, the fish will
start to bleed internally and may develop dropsy as the organs start to shut down.
- 50% or more water change Immediately.
- Keep ammonia levels below 1 PPM.
- Discontinue or reduce feeding.
- Lower Ph to below 7 - slowly.
- Use Amquel or Prime or some other ammonia neutralizing product (Be careful with Amquel if you have soft
water - it can crash your pH)
Amquel and other such products are temporary stop gap measures only and no substitute for water changes.
You have often heard me preach at the pulpit of fishless cycling. Many new hobbyists consider the choice to
cycle fishlessly or with fish to be simply that - a choice. Any aquarist, who understands how corrosive ammonia
is and how badly it affects their fish, will not willingly make the choice to subject their fish to a cycling
a tank again.