Signs & Symptoms of Ammonia in Fish Tanks

Ammonia is an "invisible assassin," according to Fish Channel.com. Its only acceptable level in tanks is zero. It enters via three methods. Its least likely source is improperly treated tap water. Decomposing organic matter such as dead fish or too much fish food cause ammonia levels to rise. Since ammonia is excreted from fishes' gills, overcrowded aquariums facilitate high ammonia levels. Because ammonia is colorless and water soluble, clear, sparkling tanks aren't indicative of ammonia-free environments.

  1. Imperfect Filtration

    • Filtration, or the filter system, is a tank's means of removing (outputting) ammonia. If filtration is limited, for example with an undersized filter, ammonia accumulates quickly. The classic period for ammonia accumulation is when a tank, its fish and filter system are new. This is known as "New Tank Syndrome" and can be avoided by the gradual addition of fish and frequent water testing while building the tank to safe capacity. When ammonia is definitely not caused by "New Tank Syndrome," filters must be checked for blockages, reduced flow and excess debris.

    Water Temperature and pH Level

    • Ammonia exists in two forms, free or unionized ammonia (NH3) and ionized ammonia, called ammonium (NH4). Ammonium is less toxic, but still a major concern. The proportion of toxic to less toxic ammonia depends on the water's pH level and temperature. The higher the pH and temperature, the greater the proportion of highly toxic unionized ammonia. According to Fish Channel.com, a pH of 8 ammonia is 10 times more toxic than a pH of 7. At 68 degrees Fahrenheit, it's five times more toxic than at 32 degrees. Ammonia is 30 percent less toxic in marine (salt water) aquariums but even so, the only acceptable level is zero.

    Level of Nitrite

    • Although ammonium (NH4) is the less toxic form of ammonia, it can lead to another serious problem--nitrite. When ammonium mixes with water, beneficial bacteria can convert it into nitrite (NO2). Like ammonia, nitrite is toxic and harmful to fish. It causes severe stress, respiration problems and weakened immune systems, leading to higher susceptibility to disease and death. Although ammonium facilitates nitrite, independent tests must be conducted for each.

    Unhealthy Fish

    • Ammonia is a tissue irritant, causing fish serious problems such as hyperplasia. Red streaks appear on their gills or elsewhere on their bodies. Their gills turn red or purple and gill tissues inflame and hemorrhage, causing delicate filaments to thicken and clump together. This reduces their abilities to absorb oxygen and to excrete ammonia. This is a serious problem since 90 percent of all ammonia is excreted from their gills. Effected fish exhibit pronounced gasping, usually at the water's surface. Additional signs of ammonia poisoning, also called ammonia stress, include lethargy, appetite loss, hovering at the bottom of the tank (especially for surface dwelling fish), and inflamed eyes or anus.