BULLETIN OF THE UNITED STATES FISH COMMISSION. 281 
forms of conferva the best plan is to change the water, although they 
may be destroyed by diminishing the light sufficiently or by introduc- 
ing a number of tadpoles. 
FEEDING FISH IN AQUARIA. 
In feeding the fish care must be taken to introduce no more food 
than they can eat in a short time, as what is not eaten will soon decom- 
pose and make the water cloudy, and generate noxious gases as well. 
If due care is observed in regard to quantity it does not matter how 
often fish are fed except that if fed abundantly they will grow rapidly, 
which is not generally desired. Fish may be fed every day or but two 
or three times a week with equally good results apparently. They 
will always find a small amount of food in the aquarium in the vegeta- 
tion. Where they are not fed sufficiently they are apt to strip the 
plants of their leaves. In a natural condition fish are feeding continu- 
ally and grow very rapidly. 
The wafer food which is universally sold for gold-fish and other veg- 
table feeding fishes is a good, nutritious food. Bread, cake, and cracker 
sour more quickly, and are therefore somewhat objectionable unless 
carefully used. Most fish, even those supposed to be strict vegetarians, 
are fond of raw beef. It should be scraped to get the pulp free from 
muscular fiber, or chopped very fine. Lean beef, unsalted, may be 
dried quite hard and can then be scraped quite fine. It soon softens in 
the water, but does not give off the blood as when raw. The fish, how- 
ever, prefer it raw. Ants’ eggs are excellent food. They can be gener- 
ally bought at bird stores. Oysters and clams, well washed to get rid 
of the juices and chopped fine, are enjoyed by most fishes. Worms, 
chopped fine for small fish, are enjoyed most of all. All chance of con- 
taminating the water in feeding the fish may be avoided by having an 
ordinary confectionery or other jar into which the food may be dropped 
after placing it in the aquarium. The fish will soon find their way into 
it. Many of our common brook and pond fishes will eat animal food 
only, and some of them only living things. Among such are the vari- 
ous sun- fishes, sticklebacks, etc. They are perhaps more lively and 
interesting in their habits than the more peace-loving vegetarians, the 
gold-fish and others of the cyprinidae, but there is more difficulty in 
finding food for them. A small scoop-net made with cheese cloth and 
used in almost any quiet water, among the dead leaves, will often yield 
large numbers of insect larvae, small crustaceans, which afford them 
natural and needed food. 
DISEASES OF FISH. 
Fish are subject to diseases very similar to those of other animals. 
They are sometimes infested with parasites, some of them microscopic, 
which will eventually kill them if not removed. The manifestations 
