160 riSH DISEASES 



Leeches. There is a small white leech about % inch long occa- 

 sionally introduced with living food (daphnia), more particularly in 

 the spring. This attacks the bodies and gills, and if the fish is only 

 a few weeks old the results are fatal. In an aquarium it is easily pos- 

 sible to see them on the glass and the breeder should be on the look- 

 out for them. If any are discovered the fishes should be carefully 

 removed to an aquarium where they can be kept under observation. 

 The aquarium should be disinfected by the ammonia method (page 

 149). These and larger leeches can be removed from the gills of 

 larger fishes by the injection of strong salt water, or by the pro- 

 gressive salt water treatment previously described (page 150). 



Fish Lice. While not very common, and seldom fatal, this crus- 

 tacean parasite is very annoying. It is about ji inch in diameter, very 

 flat, of a nearly rounded outline and is quite translucent, but distinctly 



Fig. ISO. Fish Louse (Enlarged four times) 



showing handsome iridescent colors under a good magnifying glass. 

 They are free swimmers and are able to hold most tenaciously to their 

 hosts. So tight is their hold that even after death by poisoning they 

 still adhere where fastened. Owing to their translucent quality they 

 are difficult to see. The fishes will scratch themselves much the 

 same as in cases of the "Itch," but one can notice small irritated spots, 

 particularly on the tail and fins. The body, however, is not free from 

 attack. The lice adhere tightly but can be picked off. If touched with 

 an equal mixture of turpentine and kerosene they will come loose. 



Flukes. The detection of flukes is not easy without the aid of a 

 microscope, the cavise being a small parasite worm (Gyrodact\lus 

 elegans), chiefly infesting the gills. The fish breathes unnaturally fast, 

 frequently coming to the surface of the water for air. The fins tAvitch 

 and occasionally 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 treat- 

 ment, which will usually efi^ect 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 shows signs of 



