Sometimes a fish becomes constipated, or is subject to a kind of stoppage in the intestines. The fish becomes usually 'out of sorts' occasionally refuses to eat, becomes thin and swims with fins closed.
In this case, the fish should be put into a little aquarium by itself and Epsom Salts added to the water-half a teaspoonful to every gallon of water.
If the trigger of the illness is in reality constipation and this treatment is efficient, the fish should pass heavy excreta. Halibut oil soaked into a little bread pill may also be tried.
Convalesce the fish by changing the aquarium water and feeding live foods for a couple of days. If this treatment should fail to cure the fish, it tends to indicate that the trouble might be because of internal growths or internal parasitic worms, in which case it would be kind to destroy the fish.