FISH DISEASES 89 



it is considered to be due to a disordered liver. It is more apt to attack 

 fancy goldfishes and tropicals, the Dwarf Gouramis being particularly sus- 

 ceptible. The manifestations are a swelling of the body and the scales 

 standing out at an angle. This can best be seen from a top view. 

 Strangely enough, the victims do not seem to feel depressed until within 

 a few days of death. See text accompanying Figure 227. 



Treatment. No cure is known for dropsy in fishes. They have 

 been known to improve under absolute starvation lasting several weeks, 

 but a recurrence is likely to take place. There is a current belief that 

 a few drops of digitalis in the water sometimes effects a cure. The author 

 has never been able to verify a single such case. 



Swimming Bladder Trouble. Highly bred, short-bodied fishes are 

 the more susceptible to this not uncommon disorder. Sometimes the 

 victims are unable to rise from the bottom except by a violent effort, or 

 again they may lie at the top of water at an angle, or even upside down. 

 Scaleless varieties are the more susceptible, particularly the light colors. 

 Reduced temperatures, even when brought about slowly, are responsible 

 for most cases. In normal condition this bladder balances the fish. 



Treatment. No sure cure for swimming bladder trouble is known, 

 but it is sometimes relieved by placing the fish in very shallow, slightly 

 salt warm water. If the patient is benefited it will always have to be 

 kept in temperate water, preferably shallow. 



It should be borne in mind that not all cases of loss of equilibrium 

 are due to bladder trouble, but may be caused by accumulated gases 

 resulting from indigestion. Treatment for constipation will relieve these 

 cases, but such fishes will have to always be watched carefully thereafter. 

 The author has had some remarkably good results in these cases by feed- 

 ing earthworms. 



Gill Congestion. There are two forms of gill congestion. The most 

 important, generally known as "gill fever," is that attacking fry from two 

 to five weeks old, and is easily responsible for more losses among gold- 

 fishes than all other causes combined. The gills become inflamed and 

 swollen, presenting a distended appearance. Owing to the minuteness 

 of the fish at this period a further observation is difficult except with a 

 magnifying glass, which shows white threads like bristles sticking from 

 the gill plates and openings. The disease is highly contagious, so that if 

 one affected fish is found in a thousand, it is very difficult to save any 

 of them, even though the sick fish be removed at once. 



The other form affects mainly young fishes about 2 inches long. The 

 gills swell rapidly, the infection spreading to the throat and producing 

 a gray or whitish appearance. Without treatment, death is sure to come 



