Fish as Pets
Some authorities believe fish to be the most numerous pets in America. Fish owners in the United States have been estimated at between ten and twenty million, and most of these have a half dozen or more pets.
No kind of pet varies more from one species to another than fish, and the aquarist must be aware of the peculiarities of his own types if he is to be successful. However, there are certain generalizations that can be made.
Goldfish are easiest to raise, requiring only to be fed and to have their water changed occasionally. They are remarkably rugged and survive great changes in temperature, if the changes do not take place too suddenly. They have been known to live in outdoor pools that are frozen over all winter. They can survive out of water much longer than the average fish and have remarkable ability to adapt their size to their environment. A goldfish kept in a small bowl will remain small; the same fish in a large outdoor pool may grow to a length of more than a foot.
Tropical fish are much more delicate. For successful breeding they should be kept in aquariums where the temperature of the water remains constant; between 75° and 80°F. is the best temperature for most species. Unless the fish are kept in an air-conditioned room, thermostats and heaters may be necessary, particularly in northern areas. These may be bought to fit aquariums of almost any size, or may be homemade.
Sanitation and Other Care
Sanitation is important with fish, as with other pets. The glass of the aquarium should be kept clean, either by emptying the aquarium and washing it or by scraping the inside with a sharp knife or razor blade. The water must also be kept clean, either by frequent changes or by filtering. Automatic filters may be purchased and are the most practical solution for any except the smallest aquariums. Bacteria may form an oily-looking film on the surface of the water which may be removed by simply taking newspaper and spreading it gently over the surface, blotting it clean. Snails and small catfish will help keep the bottom clean, but the aquarist may have to clean it manually at times. For this, small nets or dip tubes that suck the filth up from the bottom may be used. These, or more elaborate devices, may be made or purchased from any store selling aquarium material.
No aquarium should be overcrowded. When too many fish are placed in one body of water, there is not enough oxygen to supply their needs. Goldfish in small bowls will be seen to come to the surface as though trying to get extra air- which is exactly what they are doing. Aerators are made to fit almost all types of tanks, and these will roughly double the tank's capacity. An aerator combined with a filter will supply air and keep the water clean in one operation.
The breeding habits of fish vary so widely that it is impossible to generalize about them. However, most live-bearers are cannibalistic, and the young must be separated from the adults immediately after birth if they are to survive.
The beginning aquarist is often inclined to overfeed his pets. It should be remembered that at a hearty meal a human being will eat, roughly, one eightieth his own weight. A fish may eat, in proportion to its weight, slightly more than this, but for most fish this is still a very small amount. The best rule is to feed only what the fish will eat quickly from the surface without allowing any perceptible amount to sink to the bottom. Since most fish eat during the day, they should be fed while the lights are still on, preferably once in the morning and again in the late afternoon.