Nitrites

[jlk]

Ok Kimberley I found a little advice online here it is:

Treatment:

Large water change
Add salt, preferably chlorine salt
Reduce feeding
Increase aeration

The addition of one half ounce of salt per gallon of water will prevent methemoglobin from building up. Chlorine salt is preferable, however any aquarium salt is better than no salt at all. Aeration should be increased to provide ample oxygen saturation in the water. Feedings should be reduced and no new fish should be added until the tank until the ammonia and nitrite levels have fallen to zero.
Nitrite is letal at much lower levels than ammonia. Therefore it is critical to continue daily testing and treatment until the nitrite falls to zero.

I am sorry bit I have to disagree with some of this advice. I have never heard of 'chlorine salt'- do you mean sodium chloride? Sodium chloride (NaCl) IS aquarium salt or kosher salt or canning salt. 1/2 an ounce (3 tsp) of salt per gallon is alot of salt for a freshwater fish and many scaleless and sensitive fish would not handle this amount of salt very well. A low dose of salt can be added to help combat nitrite poisoning (1/2 to 1 tsp/g) if the fish are salt tolerant but the simplest solution is water changes with a good water conditioner. Thats it.