92 FISH DISEASES 



coming to the surface of the water for air. The fins twitch and occa- 

 sionally the fish will dash wildly and aimlessly about the tank, coming to 

 a rest after exhaustion. Before death the body becomes thin and 

 emaciated. 



If the fish is not too far gone it will stand the formaldehyde treatment, 

 which will usually effect a cure. Place the fish in a solution of 5 drops 

 of formaldehyde to the quart of water. Add one drop per minute (per 

 quart) until there are ten drops to each quart. Allow the fish to remain 

 in this for ten minutes unless it sooner shows signs of exhaustion. Return 

 to a thoroughly disinfected tank and repeat the operation next day. Two 

 or three treatments will usually be sufficient. As a rule, all the fishes in 

 a tank are affected, so if this parasite is positively identified, it will be 

 well to treat every fish that has been exposed. 



Most animal parasites can be destroyed by adding 1 part of glacial 

 acetic acid to 490 parts of water. Treatment lasts twenty seconds. 



Ichthyophthirius. If a dangerous disease may be called interesting, 

 ichthyophthirius would be entitled to that distinction. Of recent years 

 it has been the centre of attention among aquarists and writers in 

 aquarium periodicals. It has no doubt killed more prized tropical 

 aquarium fishes than all other diseases combined. Numerous goldfishes 

 have also succumbed. 



The disease is caused by an animal parasite, spending one stage of 

 its development in or on the fins and bodies of fishes. Its presence is 

 made known by the appearance of tiny white spots, which eventually 

 become so thick as to produce a whitish appearance. One illiterate fancier 

 rather aptly called it "pepper and salt fungus" because the fish appeared 

 as though seasoned with salt. The spots are considerably smaller than 

 pin heads, yet not difficult to see. 



Formerly this parasite was always found to be fatal, but since we 

 understand its life history or cycle, it can usually be destroyed. The 

 tiny organisms which have embedded themselves in the flesh and fins 

 of their victims soon drop eggs to the bottom of the aquarium. The 

 parent parasite soon dies, the eggs hatch, become free-swimming, burrow 

 into a fish and start the cycle over again in hugely increased numbers. 



Mercurochrome, of the usual strength as purchased in drug stores, 

 used at a ratio of 4 drops to the gallon of water, is one of the surest 

 remedies. Plants and fishes need not be removed from the treated tank. 

 The temperature during treatment should be kept at about 85 degrees, 

 regardless of what medication is used. The treatment usually produces 

 improvement within 2 days, and a cure within a week. After the cure, 

 most of the water should be siphoned off, care being taken to remove all 

 sediment. If the fishes are large enough to handle in a net, the mercuro- 



