Aquariums Getting Into the Swim

By Diane G. Elliott.

A well-maintained aquarium makes an attractive addition to a home, office or classroom and can provide hours of fish-watching enjoyment. Numerous species and varieties of ornamental fish are available to suit almost any budget and taste. Modern aquarium products have made ornamental fish-keeping increasingly simple.

A basic knowledge of the principles of aquarium maintenance can help to make an aquarist's fish-keeping experiences enjoyable and rewarding. The following discussion focuses on general procedures for setting up and maintaining a freshwater aquarium, but some of the general principles apply to marine aquariums as well.

A bewildering array of glass and Plexiglas aquariums from familiar rectangular tanks to more fanciful shapes such as hexagons and globes is available to the aquarist. The selection of a particular aquarium shape is partly a matter of esthetics, but not all aquariums of the same water capacity have the same fish-holding capacity.

The area of water exposed to the air is perhaps the most important factor for determining the number of fish an aquarium can safely hold. A shallow 15-gallon tank with a large air surface area can hold more fish than a tall 15-gallon tank with little surface area.

The best size of aquarium to select depends on your budget, personal preference, available space, and perhaps most important the types of fish to be kept. In practice, following initial setup, routine maintenance required for a large aquarium is about the same as for a small one. Furthermore, rapid (and undesirable) fluctuations in environmental conditions (temperature, for example) are less likely to occur in a larger volume of water than in a small.

Setting Up

Clean an aquarium with tepid water and salt only, no detergents or soaps. After rinsing, move it to its final location before filling with gravel and water. Avoid locating the aquarium near strong heat or strong drafts, near sources of toxic fumes, or in direct sunlight. The latter will bring excessive algal growth.

Aquarium gravel is now available in a rainbow of colors, thanks to a process that coats gravel particles with non-toxic colored materials. Natural gravel is also available. All aquarium gravel, even that labeled as prewashed, should be rinsed thoroughly with water to remove silt. Unrinsed gravel may cause cloudiness of the water, and the suspended particles may irritate the gills of fish.

For an attractive display, about two pounds of gravel are recommended for each gallon capacity of the aquarium. The gravel bed is generally sloped (for example, from about 3 inches deep at the rear of the tank to about half an inch deep at the front) so solid wastes will collect at the front of the tank for easy removal by siphoning. Perhaps the best way to fill an aquarium with water without disturbing the gravel is to pour the water slowly into a bowl placed on the gravel.

Water used directly from the tap often is not satisfactory for aquarium fish. Most municipalities chlorinate their water supplies, and chlorine is toxic to fish. Chlorine can be neutralized easily and made safe for fish by adding sodium thiosulfate, which is available in pet supply shops under various trade names.

Adjusting pH

Water pH may need adjustment. The pH is a measure of the hydrogen ion (H+) concentration in the water. The greater the hydrogen ion concentration, the lower the pH value. A pH value of less than 7 is acid, a pH value of 7 is neutral, and a pH value higher than 7 is basic or alkaline.

The optimum pH for a particular aquarium will depend on the types of fish and plants kept. The preference of most freshwater aquarium fish falls in the range between pH 6 and 8.6. Many plants prefer a neutral or slightly alkaline pH. Simple pH test kits accurate enough for aquarium use can be obtained at pet supply stores, and buffer chemicals for adjusting pH also can be purchased there.

Water hardness also can be measured with an inexpensive test kit. Hardness is a measure of the total dissolved salts, principally calcium and magnesium, in the water, and is frequently expressed as the total amount of calcium carbonate present. Soft water, water with low concentrations of dissolved salts, is usually acidic; and hard water is alkaline.

Some fish species prefer soft water while others prefer hard, but none thrive in distilled water. Some salts must be present for proper physiological functioning. Salt mixtures for increasing the hardness of very soft water are available at aquarium supply shops.

Decorations selected for an aquarium are largely a matter of personal choice. Many non-toxic ornaments such as plastic plants are sold by aquarium supply shops.

Plastic plants generally are realistic in appearance and are particularly useful for aquariums housing plant-eating fish. However, many aquarists prefer to grow live plants. Some aquarium plant growers now supply plants in small pots or cushions impregnated with a supply of slow-release fertilizer, so that plants will obtain an adequate nutrient supply even in a new aquarium.

Rocks, Driftwood

In addition to plants, materials such as rocks or freshwater driftwood, if waterlogged or weighted, make attractive aquarium decorations. Exercise caution in selecting such decorations, however, as some rocks and wood contain salts or other soluble substances, such as copper, which may be harmful to fish.

Seashells and shell grit, sometimes used in place of sand, are occasionally observed in freshwater aquariums. These materials dissolve in the water, making it too hard or alkaline for many fish species.

Books on aquarium management frequently contain suggestions and diagrams for arranging plants or other decorations. An often-stated rule of design is that taller plants and other tall decorations should be placed toward the back and sides of the aquarium, with smaller plants and short decorations towards the front. Leave some open swimming room for the fish. Some decorations such as rocks are easier to arrange when a tank is empty. Others such as plants are easier to manipulate when the tank is at least partly filled with water.