NITRITE SPIKES

     Nitrosomonas is the heterotrophic bacteria credited with the initial stage of biological filtration of converting ammonia waste released by the fish into the second stage nitrite. Once it is established this bacteria is very hardy and efficient. After the initial start-up and cycling of an adequate filter detectible amounts of ammonia should not be common.

     Nitrobacter is the heterotrophic bacteria credited with the second stage of biological filtration of converting toxic nitrite to the much lesser toxic nitrogen compound nitrate. Nitrite can be more toxic to fish than ammonia and be a more common problem. Sometimes called “New Pond Syndrome” high nitrite levels that occur after a few weeks after initial set-up is responsible for many new pond mortalities. Nitrite binds with fish red blood cells causing gasping and “Brown Blood Disease”. Fish that have died with their gills widely flared are though to have died of Nitrite induced “met-hemoglobin-emia”. Unlike Nitrosomonas however the bacteria Nitrobacter is slower to develop and is much less hardy. It is not as robust and is easily compromised by chemical treatments and changes in water quality including temperature. It is much more common to have high Nitrite readings after a filter has fully cycled. This is called a “Nitrite Spike”

     Temperature can greatly affect nitrobacterium and detectable nitrite levels in a pond. Cold spells where water temperatures suddenly drop will cause a nitrite spike. During a recent cold spell a 5,000 gallon pond with good filtration had over 2.0 parts per million of nitrite. Fish became sick before this was noticed. The water temperature had only dropped to 63 degrees F for this to happen.

     Treatments for high Nitrite levels are regular water changes and reduced feeding. However water changes can add chlorine and released ammonia so proper treatments like Amquel-plus should be used. The addition of salt will inhibit the uptake of nitrites.

     Ich is also suspected in these suddenly cool ponds. Several had fish jumping and acting odd. After adding salt at 0.3% (about 3 pounds per 100 gallons) all ponds started acting normal. Unchecked we would expect fish coming down with health problems. The cooler weather can initiate more than one problem. It can by effecting filtration and water quality. Cooler temperatures can affect the immune system in the koi and give parasites an opportunity. Combine any two or add all three and serious problems can occur. Using salt was a good choice for this condition because it prevented nitrite uptake, is a good long term Ich medication which is needed for the longer life cycles of sixty degree water and will not harm an already compromised biological filter. Salt also is anti-bacterial and helps koi physiology.

     In closing careful monitoring of water quality conditions is important year round and at the first sign of change. Monitoring temperature is a good indicating watchdog. Nitrite spikes may be more common that ammonia problems. The use of Salt is a good treatment for cool water and nitrite spikes.