Best Fish Tank: How to Choose the Right Aquarium for Your Fish

What matters most: size and stability

Water volume is a buffer. In a small tank, waste, temperature and chemistry change quickly, and one missed water change can harm fish. In a larger tank, the same mistake is diluted. That is why experienced keepers suggest beginners start with 20 gallons rather than a tiny bowl.

VCA's rule of thumb is about one gallon per inch of adult fish, and it depends on the species: some fish grow much bigger than they are when sold. Research the adult size of every fish you plan to keep, then choose the tank from our fish tanks.

Glass vs acrylic, and tank shapes

Glass tanks are scratch-resistant, clear for years and less expensive, but heavy. Acrylic tanks are lighter and less likely to shatter, which suits large tanks, but scratch easily during cleaning. Rimless tanks look sleek; rimmed tanks are more forgiving of uneven stands.

Long, shallow tanks give more surface area for oxygen exchange and swimming room than tall, narrow ones of the same volume. Bow-front and cube tanks look attractive but give less swimming length. For active fish, length matters most.

Kits vs buying separately

Starter kits bundle a tank, lid, light and filter, sometimes a heater, and are convenient for 10 to 29 gallon setups. Check that the filter is rated for the tank's volume, because kit filters are often the weakest part.

Buying separately lets you choose a stronger aquarium filter and a heater suited to your fish. VCA says every tank needs filtration and a thermometer, and that a heater may be needed depending on species; most tropical fish need stable warm water.

Best tank for each situation

For a first community of small tropical fish, a 20 gallon long tank with a filter and heater. For a single betta, VCA notes only one male per tank; a 5 to 10 gallon heated, filtered tank is far better than a bowl. For goldfish, which grow large and produce a lot of waste, a much bigger tank with strong filtration.

For apartments, check floor loading: water weighs about 8.3 lb per gallon, so a filled 55 gallon tank with gravel and stand weighs well over 500 lb. Use a stand rated for the tank.

What to avoid

Avoid bowls and tanks under 5 gallons for nearly all fish, and avoid adding fish the same day you set up. VCA recommends running the filtered tank for 4 to 6 weeks before adding fish so ammonia and nitrite levels settle.

Avoid direct sunlight, which causes algae and temperature swings, and avoid placing the tank in the path of an air conditioning vent, as VCA advises. Avoid overstocking and overfeeding, the two most common causes of fish loss.

Maintenance and lifespan

Test water regularly, clean the filter as the maker directs, and change part of the water every 2 to 4 weeks, as VCA suggests. Use a water conditioner to remove chlorine from tap water. Wash your hands after working in the tank, as the CDC advises after cleaning any animal habitat.

A glass tank lasts many years; check silicone seams for peeling and replace a tank that leaks. Fish that gasp at the surface, lose color, stop eating or show spots or ragged fins need water testing and advice from a vet who treats fish. When you are ready to set up, our fish tanks and aquarium supplies cover the tank, filter and accessories a new aquarium needs.

This page is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your pet.