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20-gallon tank setup: What fish and supplies do I need to get started?

Updated On September 23rd, 2025

I have a 20 gallon tank. I'm thinking of buying +5 fish. Which fish could I buy and what would I need for the fish and tank?

1 Answer

Most Helpful Answer

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Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on November 23rd, 2017

A fish tank will need a filter, a light/hood and a heater. Make sure the filter is rated for at least twice the tank volume. The heater should be adjustable since water temperature will depend on the species of fish. Good "starter" fish include Tetras, Mollies, Danios or Tetras. A new tank should be set up and left running empty for several weeks before adding fish. A pinch of flake food can be sprinkled in daily. This "cycling" will allow a population of beneficial bacteria to colonize the tank and filter. These bacteria will break down wastes (ammonia, nitrites and nitrates) which are toxic to fish.

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