Proper Care

Properly cared for aquariums are beautiful microcosms--little miniature ecosystems of their own. However, this beauty requires some careful setup and regular maintenance. The requirements of an aquarium are not too taxing, but they must be met if the fish are to remain healthy.

Size and Inhabitants

There are a number of factors to consider when choosing aquarium inhabitants:

  1. Temperament
  2. Adult size
  3. Water chemistry
  4. Temperature
  5. Diet

Because the water chemistry cannot change as fast in a larger volume of water, larger aquariums are actually easier to maintain. Recommended minimum sizes for beginner aquarium keepers differ between freshwater and saltwater tanks:

  • Freshwater: 20 gallons
  • Saltwater: 55 gallons

The surface area of the water is equally as important as the number of gallons it holds, because the surface area determines how much oxygen can be exchanged between the water and the air.


Some fish will only eat live food, which should be a major consideration when choosing an aquarium's inhabitants. Herbivores should not be kept with carnivores because their nutritional needs differ too widely. Many common aquarium fish can be kept on a basic flake or pelleted food designed for their species, but it is worth noting which ones cannot.


A well-maintained aquarium has three types of filtration going on at any one time: mechanical, chemical, and biological. Filter floss removes debris and carbon helps clear the water. Biological filtration occurs when "good" bacteria grow in sufficient numbers in the aquarium to neutralize the ammonia the fish produce in their waste.

In a new aquarium, the numbers of good bacteria are low and ammonia is relatively high. Because of this, new aquariums must either have a few very hardy fish placed in them for the first three to four weeks, or the aquarium must remain empty but with the filter on, while the aquarist adds pure ammonia every day. After about three to four weeks, the ammonia levels will drop to zero and new fish can be added a few at a time.

Water Parameters and Lighting

The main components of water chemistry that aquarists need to test for are pH, ammonia, and water hardness. Saltwater aquariums must also maintain salinity levels. Ammonia should always be maintained as low as possible.

Because the pH scale is logarithmic, the difference between 7.0 and 9.0 is much more than twice the difference between 7.0 and 8.0. Most fish can only be healthy in water that is maintained in a relatively small range:

  • African lake fish require a pH of 8.0-9.0 and very hard water
  • Community aquarium fish usually do best at a pH of around 7.0 and medium hardness
  • Riverine fish from South America may require a pH as low as 5.0 and very soft water
  • Saltwater fish require a pH of between 7.6 and 8.4

Most aquarium fish are tropical and also require a heater. Only a few of the commonly-kept species will do well in a coldwater tank. Temperatures in the 72-80 degree Fahrenheit range are typically needed to keep aquarium fish healthy.

In addition to chemistry and temperature, lighting is very important in a planted tank. In a fish-only aquarium or one with fake plants, lighting only needs to be sufficient to show off the inhabitants. However, a planted tank will require specialized light bulbs that provide the wavelengths and intensity required for plants to thrive.

Day-to-Day Maintenance

Aquariums are relatively low-maintenance once they are set up. However, they do require feeding and regular testing of water levels, temperature, and salinity (if applicable). Filter cartridges also need to be rinsed or replaced, and algae must be removed.

Water changes are required in order to maintain proper conditions, but the number and timing of these depends on the fish species in the tank. Common community fish will do well with a 20 percent water change every two to four weeks. The water must be treated to remove chlorine and adjust chemical parameters and temperature before it can be added to the tank, so the process requires a bucket, testing supplies, and some water treatment chemicals.

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