Question: I decided to fix up my tank. I put the fish into another vessel, cleaned everything properly and filled the aquarium with tap water, as my pall told me. And I guess I brought some pathogens inside: the fish try to jump out of the tank.
Answer: Your fish may have got ill. The disease is called chlorosis, but is caused not by the pathogens but by an excess of chlorine in water. In order to fight germs the chlorine is added to the city water. Its concentration may reach 0.1 mg/l in winter, and in frost-free season (especially in spring) may rise up to 0.5 mg/l. That time you may even feel that the water smells this gas.
Chlorine acts bad on fish. When its content exceeds 0.05-0.1 mg/l, the fry and young fish die within 2 to 3 hrs. Concentration of 0.03-0.05 mg/l kills the fish spawn.
Gills are exposed to toxic action of chlorine in the first turn. They become covered with slime and their tissue is gradually destroyed. On the second place are the fins (they die off too) and the trunk (it becomes covered with mucus).
At first stage the fish behave uneasy, they make rotatory hitches, trying to jump out of the tank. Later on, to the contrary, they do not react on anything.
The treatment is as follows. Before pouring the water into the tank, chlorine should be removed: fill a wide glass or enamel dish with tap water and leave for 24 hrs or better - two days. If you already have water prepared in such way, you can replace the tank water with it, at least partially. The quicker way is heating the tap water to 194 пїЅF within 30-40 min. The chlorine also evaporates when the water is actively aerated during 24 hrs or is passed through an activated charcoal.
By Lyudmila Stushkovskaya. 1000 advices about how to treat pets
Translated by Tatiana Karpova (Moscow)
(MSU, Biology faculture, Dep. zoology and ecology).