TROPICAL AQUARIUM FISHES 153 



treatment can go far to relieve this condition and ward off permanent 

 blindness. 



Treatment. Make a saturated solution of boracic acid in tepid 

 water. This is gently applied daily to the affected parts by a bit of ab- 

 sorbent cotton. The fish should be placed, if possible, in a large tank free 

 from obstructions, that the injured eyes may not be further irritated. 



Ichthyopthirius. This parasitic disease causes small whitish dots 

 all over the fish. It is more apt to affect tropical fishes and has killed 

 many fine specimens. Until recently it has been considered incurable, 

 but two cures are now positively known. The fish should be placed in a 

 plain glass jar and have the water changed (keeping temperature even) 

 every eight hours, disinfecting jar each time. This takes a few days. 

 It is claimed that plain water is as good as salt for this treatment, but the 

 writer has had better success with brackish water, gradually increasing 

 the strength and then as gradually reducing. 



The second method of treatment is only suited to goldfishes. This 

 consists of treatment in water in which two grains to the gallon of per- 

 manganate of potash have been dissolved. In a few days the old mucous 

 coating of the fish peels off and leaves a new, healthy surface. 



Animal Parasites. There are only three of these of sufficient impor- 

 tance to keepers of aquarium fishes to require mention. Food fishes and all 

 wild species are more or less subject to numerous parasites, many of them 

 serious or fatal. No doubt aquarium conditions are not favorable to their 

 propagation ; otherwise we would have more trouble in this direction on 

 account of the large numbers of wild fishes being imported for aquarium 

 purposes from all temperate and tropical parts of the earth. 



Leeches. There is a small white leech about J4 i^^ch long occasionally 

 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 possible to see them on the 

 glass and the breeder should be on the lookout for them. If any are dis- 

 covered the fishes should be carefully removed to an aquarium where they 

 can be kept under observ^ation. The affected aquarium should be disin- 

 fected and the plant destroyed. These and larger leeches can be removed 

 from the gills of larger fishes by the injection of strong salt water, or by 

 the progressive salt water treatment previously described (page 144). 



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

 parasite is very annoying. It is about ^ inch in diameter, very flat, of a 

 nearly rounded outline and is quite translucent, but distinctly 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 



