Fish Tank Setups: Tank Sizes, Betta and Goldfish Tanks

Set up a home aquarium in this order: pick the tank size for the fish you want, buy the gear on the checklist, then cycle the tank for 4 to 6 weeks before any fish go in, as VCA advises. A first tank of 10 or 20 gallons is easier to keep stable than a small one.

The chapters in this section cover the whole tank: what to buy, how big to go, and the two most common first fish, the betta and the goldfish.

Choose the tank size first

The size decides almost everything else: the filter and heater ratings, the stand and how many fish the tank can hold. VCA suggests 10 or 20 gallons for a first tank. Aqueon’s standard glass tanks run from 5.5 gallons, about 62 pounds filled, to 75 gallons, about 785 pounds filled, so check that the stand and floor can carry the weight. Fish tank sizes compared has the dimensions and weights for every standard size.

Buy the gear before the fish

A new tank needs a lid, a filter, a heater and thermometer for tropical fish, a light on a timer, a water conditioner, a test kit and substrate. The fish tank supplies checklist lists each item with the size that fits your tank. Kits that bundle the tank, filter and light are the simplest start.

Aquarium starter kits with filter and light

Shop aquarium kits with filter and light→

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• 5 to 10 gallon kitsBrowse →
• 20 to 29 gallon kitsBrowse →
• 40 gallon and upBrowse →

Place the tank before you fill it

A filled tank is heavy and hard to move, so choose the spot first. Aqueon lists its standard 55 gallon tank at 625 pounds full, and the Marina kit manual says a filled tank should sit on a level, sturdy surface, checked with a level.

VCA says to keep the tank shielded from direct sunlight and not under an air conditioning vent, and the RSPCA adds radiators to the list. Sun through a window adds light you cannot switch off and can warm the water. Pick a spot near an outlet for the filter, heater and light, with room above the tank to lift the lid for water changes.

Betta and goldfish setups compared

Bettas and goldfish are often sold for bowls, and neither should live in one. University of Illinois vets give a betta a 5 gallon tank or larger with a lid, a heater holding 76 to 81°F and a gentle filter. Bettas live alone, since two will fight.

Goldfish make a lot of waste, so the filter matters as much as the tank. An NC State aquatic vet told Vetstreet that 29 gallons is best and 20 the minimum. Most goldfish need no heater: the RSPCA in the UK gives them 10 to 21°C. RSPCA Australia says goldfish live about 10 to 15 years, so the tank is a long commitment.

Setup chapters by fish

The gear itself, from filters to substrate, is covered in the equipment section, and cycling and cleaning in tank care. Planning a marine tank? Start with the saltwater section. Buying a tank as a present? See gifts for fish keepers.