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What fish can I put in a 3-gallon tank, and how to change water?

Updated On September 23rd, 2025

Pet's info: Fish | Unknown - Fish | Male

I want Angel Alvarado to answer this question. What fish can i put in a 3 gallon tank besides shrimp. If I have to get neon tetras please tell me how to change their water. Thanks

2 Answers

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Answered By Angel Alvarado, LVT

Licensed Veterinary Technician

Published on August 27th, 2018

The small size will limit the species of fish as well as the number. White Cloud Minnows or Guppies would do fine in a small tank. You could keep no more than 2 or 3 fish total. If you are looking for company for your Betta, the same species can be kept. Other options include Otocinclus (Otos), Corys, Platys or Harlequin Rasboras. Again, no more than one or two in addition to the Betta. Water changes for any tank are simple. Change no more than 30% total volume at a time. Use a water conditioner to remove harmful chemicals and make sure the water is temperature matched to prevent stress or shock. Rinse the filter in tank water, not tap water, to preserve beneficial bacteria. Vacuum the substrate every couple of weeks.

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    Answered By Angel Alvarado, LVT

    Licensed Veterinary Technician

    Published on May 23rd, 2018

    A small tank with one Betta will require minimal upkeep. Most small HOB (hang on back) filters will be sufficient. Tetra, Fluval and Aqueon make a wide range of acceptable filters. The tank should have a cover or hood as well as a light and a heater. Bettas do best between 78 F and 80 F. Feed 1-3 pellets once or twice daily. Change the filter as per manufacturer instructions. Rinse filter media with tank water, not tap water, to preserve beneficial bacterial populations. A partial water change, no more than 20-20% of total tank volume, may be necessary every 2 weeks to maintain water quality and stable chemistry. Use only aged or conditioned water that is temperature matched to prevent stress or shock. Water conditioner brands include: AmQuel Plus, NovAqua, Prime, StressZyme and StressCoat. You don't need all of them. Follow the directions on the bottle. Allow the tank to cycle before adding a fish. This will allow beneficial bacterial populations to colonize the filter and substrate. These bacteria are responsible for breaking down fish wastes and uneaten food. A proper Nitrogen Cycle may take 4-6 weeks to complete. You will know when chemistry reads: 0 ppm ammonia, 0 ppm nitrites and 20 ppm or less nitrates.

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