54 NEW YORK AQUARIUM NATURE SERIES 



hatching and breeding tanks, to improper feeding, etc., and the 

 disease yields readily enough to proper treatment. So far as 

 known this condition does not attack inhabitants of the small 

 aquarium. 



Parasites : These may be plant or animal and are either 

 external or internal in their mode of attack. The plant para- 

 sites are either fungus {Saprolegnia, etc., or water mold), or 

 bacteria. The fungus is perhaps the most common parasite at- 

 tacking aquarium fishes. The disease is propagated by means of 

 very minute spores carried in the water. Probably fishes that 

 are in a perfectly healthy condition are not attacked, but if any 

 abrasion occurs on the skin, an opportunity is given for the de- 

 velopment of the spores, or if the fish is weak and anaemic, the 

 gills or the tails, especially in the long-tailed goldfishes, may be 

 the seat of attack. The first evidence of the disease on the skin 

 i? the presence of a white blotch or blotches, which, on close 

 inspection, is seen to be made up of minute strands (hyphae) 

 having something the appearance of absorbent cotton. If not 

 checked at once, numerous spores will be produced on the outer 

 ends of these threads, and be disseminated through the water of 

 the aquarium to the danger of other fishes. On the appearance 

 of this disease in the aquarium it is best to remove all the fish at 

 once and disinfect the aquarium thoroughly. This may be done 

 by treating the tank with a strong solution of salt, while the 

 plants may be placed for a few hours in a solution of phenol 

 .sodique (a tablespoonful to a gallon of water). The fish at- 

 tacked by the disease should be removed at once from those not 

 affected and kept separate until all evidence of the disease has 

 disappeared. For treatment they should be placed in a three 

 per cent, solution of common salt for an hour or so. If they show 

 any signs of distress, such as inability to keep their balance, 

 after they have been in the salt bath a while, they must be 

 removed at once to fresh water. The treatment should be re- 

 peated daily until all evidence of the fungus has disappeared. 

 This treatment applies also when the fungus is on the gills. If 

 the disease attacks merely the skin, it may also be treated by 

 local application of a 50 per cent, solution of peroxide of hydro- 

 gen, the fish being removed from the water for a few moments 

 while the application is made. A solution of potassium perman- 

 ganate (dark claret color) may be used in a similar way for local 

 treatment, or the fishes may be placed in a weak solution of the 



