Vet Q & AWhat fish can I put in a 3-gallon tank, and how to change water?
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.
Updated on September 24th, 2025
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