Ammonia’s Effect On Fish
Ammonia is a tissue irritant, causing real problems for delicate areas such as exposed gill tissue. The gill tissue responds to this irritation by hemorrhaging, with the delicate filaments thickening and clumping together — a condition called hyperplasia. The vast reduction in surface area caused by the clumping reduces a fish’s ability to absorb oxygen from the water. In addition to their undesirable state of affairs, any oxygen that is absorbed is done so suboptimally, as the presence of ammonia reduces the blood’s carrying capacity.
If that’s not bad enough for our fish, the reduction in the surface area of the gills also reduces a fish’s ability to excrete ammonia from its body, causing the ammonia levels in the fish to increase, damaging every cell in the fish’s body. More than 90 percent of all ammonia excreted by fish is done so by the gills. It’s not surprising therefore that when fish do experience ammonia in an aquarium, they show a pronounced and typical gasping response.
If ammonia strikes in what has previously been a mature and stable aquarium (not a result of New Pond Syndrome), then you should check the following:
1) Food and feeding. Have you (or anyone else) changed the food or fed more than usual?
2) Check the filter. Is it blocked? Is its flow rate reduced? Does the media need cleaning?
3) Fish count. Are there any fish missing? Is a dead fish decaying unnoticed behind your tank decor?
4) Too many fish? Have you recently added more fish — perhaps more than your tank can handle?
In summary, ammonia is lethal, and we should aim for zero levels at all times. Sublethal levels can also go unnoticed, causing fish stress and making them more susceptible to disease. If an ammonia spike does occur, it is likely to be in either a new aquarium (New Tank Syndrome) or due to an acute catastrophic event (overfeeding, fish death, etc.). However, rapid intervention and a mature filter will address both the problem and enable your aquarium (and fish) to recover. Fortunately, a filter will reprocess ammonia relatively into nitrite. Unfortunately, nitrite is still lethal to fish and proves to be more persistent and is a more stubborn problem to resolve — but that’s another story!
