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 look red.

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.

Suggested Treatments

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.

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