United States Department of the Interior Fish and Wildlife Service Bureau of Sport Fisheries and Wildlife Division of Fish Hatcheries

Home , Marine aquarium

UNITED STATES DEPARTMENT OF THE INTERIOR FISH AND WILDLIFE SERVICE BUREAU OF SPORT FISHERIES AND WILDLIFE DIVISION OF FISH HATCHERIES

Fishery Leaflet 411 Washington, D. C. Revised January 1965

CARE OF TROPICAL AQUARIUM FISHES

Keeping a home aquarium with small tropical fishes is a hobby followed by about ten million Americans. This hobby provides excellent relaxation and entertainment for people of all ages, but the amateur aquarist soon finds that maintenance of these toy exotic fishes involves more than merely putting them in some water and throwing in prepared dried food at irregular intervals. Fish fanciers who have successfully pursued their fascinating pastime have discovered that all fish require proper attention and intelligent care if they are to be kept alive and healthy under the artificial conditions in an aquarium, and that each species of fish has its own needs for normal growth and reproduction.

Although many species of home-aquarium fishes occur in nature over a wide environmental range, general rules that are applicable to the care of all aquarium fishes have been established. Four things are essential to a successful aquarium: 1. Suitable water; 2. Sufficient oxygen; 3. Correct temperature; and 4. Correct feeding. To approach the problem of maintaining an aquarium from another direction, the following may be listed as the main causes for failure: impure vater, overcrowding of fish, sudden temperature changes, overfeeding or improper food.

1. Suitable water: Water that is supplied to homes in most cities and l arge communities is poisonous to aquarium fishes--goldfish as well as tropical fish. Such water usually contains chlorine to render the water sterile and safe for human consumption, but this chemical is decidedly injurious to all fish. All chlorinated water should be drawn from the faucet and allowed to remain in an open glass or enamel container at least 24 hours before being used for fish. Deep well or artesian water should also be avoided because it often contains a large amount of injurious minerals. Well water that lacks a high mineral content and most clear waters from ponds, lakes, and streams are satisfactory for aquarium use. Highly acid swamp water and fresh rain water should be avoided. Rain water that has stood several days and contains a teaspoonful of rock salt to the gallon of water may be used. In brief, when an aquarium is started, all water should be allowed to stand several days in the tank before fish are intro- duced; water that is added should be held at least 24 hours before being placed in the aquarium. When possible, at least some water from an old established aquarium should be utilized in a new aquarium. As an aid in maintaining clear and healthy water in an aquarium, filters using activated carbon and fiber glass and operated by an electric air pump are often used

(This leaflet supersedes Leaflet FL-165, "Some Tropical Aquarium Fishes.") by the hobbyist. However, a more recent development which seems to work very well and also uses an electric air pump is the under sand or gravel filters.

2. Sufficient oxygen. The problem of maintaining sufficient oxygen in the aquarium is closely associated with the possibility of overcrowding the tank with fish, with the temperature of the water, and with the diverse oxygen requirements of the many popular varieties of tropical toy fishes. The water in an aquarium is dependent largely upon the oxygen absorbed from the air at the surface of the tank. A straight-sided aquarium, of 3 to 20 gallon capacity, i s much better for the care of fish than a bowl or globe, which seldom holds more than a gallon of water. It is often recommended that 25 square inches of surface be allowed for each inch of fish. Plants in the aquarium are very decorative and are useful as refuge for fish in the tank but, contrary to general opinion, do not provide fish with the required oxygen. Electric air pumps, often used to circulate the water in the aquarium, permit more rapid contact of the water with the air surface and thus aid oxygen absorption. It is well to remember that water at 750 F. holds more oxygen than water at 0 85 F., and it is advisable to keep the water temperature at a minimum safe l evel to secure maximum oxygen content in the aquarium water. It is recommended that the beginner understock his aquarium: He should start with a pair of tropical fish and add gradually to the collection, at the same time watching the behavior of his fish after each addition. When the fish in an aquarium come to the surface and remain there almost continually, it is usually a sign of insufficient oxygen resulting from overcrowding or overfeeding.

3. Correct temperature. Most aquarium fishes will tolerate a temperature 0 range of about 10 F. The usual temperature range for most popular tropical fishes is from about 72° to 80° F., but goldfish do better at a lower temperature. Sudden changes in temperature are fatal to most fish, regardless of whether the temperature is raised or lowered. When the water is being changed or fish are being transferred from one tank to another, differences 0 of more than 2 F. should be avoided. Most home aquariums do not receive sufficient heat at night during the winter. It is harmful to have the water ° in the aquarium reach 80° F. during the day and fall to 65 F. or lower at night. Electric aquarium heaters with thermostat controls are available, enabling the hobbyist to maintain constant warm water in the aquarium althoUgh these heaters are best used in larger tanks. For an aquarium of less than 5-gallon capacity, a 15 to 40 watt light bulb may be hung over the water for heat. Many tanks are illuminated with a light and reflector in order to show off the fish to best advantage as well as to provide a degree of heat from the electric bulbs. Placed by a sunny window, an aquarium may not only absorb so much sunshine that the tank and its inhabitants become overheated and the water becomes green with minute plant life, but may also be chilled by cold air through the cracks in the window sash.

4. Correct feeding: The amount of food eaten by aquarium fishes is largely determined by oxygen content and temperature of the water, as both factors have a direct effect upon fish metabolism or body activity. Usually, the warmer the water (well supplied with oxygen), the greater the movement and the greater the hunger of the fish. The fish should not be fed more than they will consume within five minutes. Uneaten food must be removed promptly to prevent fouling of the water and lowering of the oxygen content. Snails and scavenger fishes are frequently kept by the fancier to help -2- remove uneaten bits of food, but it is wiser to use care in feeding. Feeding twice daily is recommended for most tropical fishes in the home aquarium.

There are many suitable brands of prepared dried fish foods on the market, although no experiments have been made to evaluate the merits of each. The usual packaged food consists of fish or meat meais mixed with coarse flour or some cereal. Dog meal, finely ground, makes an acceptable food for many aquarium fishes, as do the several varieties of dried baby cereals. Live or fresh foods such as daphnia, tubifex, mosquito larvae, white worms, and chopped earthworms are recommended for use with the dried foods. Scraped raw liver, fish, and shrimp are also excellent. The young of most tropical fishes are so small that they must be given microscopic foodstuffs such as brine shrimp, infusoria, micro-worms, and powdered egg yolk.

Strict observance of the foregoing general rules will go far in preventing sick fish in the home aquarium. It is far easier to keep fish healthy than to cure them of the many diseases to which all fish are subject. It is well to remember that most tropical fishes are short-lived when compared with other pets such as dogs and birds. Guppies and fighting fish seldom live l onger than two years under ideal conditions; and all fish, as they age, become susceptible to infectious diseases for which there are few known remedies. It is often wise, therefore, to obtain only young fish for the home aquarium instead of starting with the more beautiful but shorter-lived adult fish.

The colorful and interesting varieties of tropical fishes suitable for the home aquarium are so numerous--there are several hundred--that it is impos- sible to discuss them in this brief publication. It is suggested that the hobbyist refer to the periodicals and books listed under SUGGESTED READING for complete information. Excellent literature at popular prices helps to make the keeping of a home aquarium both enjoyable and entertaining.

SALT-WATER AQUARIUM

In recent years many aquarists have turned to marine aquarium fishes as a novelty in their hobby. In general, the same rules apply to the successful maintenance of a salt-water aquarium as to a fresh-water one. However, a marine aquarium must have a good filter and aeration device, for the salt water must be free at all times of waste materials and uneaten food. A stock of pure sea water is essential to begin a marine aquarium, although some use can be made of artificial sea water (made from sea or Turk's Island salt). Evaporation of water from a salt-water tank must be replaced with fresh water only--not with more salt water.

Colorful marine tropical fishes for a home aquarium include the french, blue, queen, and yellow angelfish, the butterfly fish, the file fish, and the puffer fish. Other interesting animals for a salt-water aquarium are sea anemones and starfish. Hobbyists who live near the seashore can readily find a host of interesting marine creatures that are suitable for observation i n a home aquarium. It is important not to overcrowd the tank, however, as this would mean the prompt death of the inhabitants of the aquarium.

A fairly recent development which has proven of inestimable value to the marine aquarist is the sub-sand filter, several types of which are now on -3- the market. This device, which draws the water through the bottom sand ( which acts as a filter) makes it possible to keep the water clear and free from harmful bacteria for a great length of time without changing it. It also eliminates the old danger of "dead spaces" and bacterial pockets under the sand, which tend to occur much more frequently in a marine aquarium than in a fresh water one.