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Q: Anon wrote,

What is the best way to change the water in a 2 gallon bowl? Where do you put your fish while you clean out your aquarium?

A: People have different methods for cleaning out their aquariums. Some decisions are based on the type of set up, the volume of water you’re changing, the equipment you have on hand and of course, personal preference. For small bowls like your 2 gallon [7.5 liter] without a filter, full 100% water changes are best. This is how I might do it.

1. Check the exact water temperature of your water and make note of it.

2. Catch your Betta in a cup. It’s advised to use a plastic cup rather then one from home. Glasses or mugs that have been washed with soap can expose the fish to residue that can be harmful. I usually keep the platic cup and lid that the fish came with and use that, rinsing it in hot water after each use. I do not suggest holding the fish in a sink. Harsh clenser residue can be dangerous… not to mention if the drain gets pulled. Yikes!

3. Drain the fish bowl and rinse the substrate several times with hot water. Use an aquarium sponge or cloth to wipe away algae or scum from the glass.

4. Give a few final rinses in cool water and then adjust the tap to meet exactly the previous water temperature. Adjust as necessary. Don’t rely on your hand to guage the temperature. An aquarium thermometer is very inexpensive and can be picked up at any LFS for less than a couple of dollars.

5. Add your water conditioners and float the fish in the plastic cup (or add to fish bag if preferred) and float in the tank. Every 5 minutes or so add a little of the tank water to the bag allowing the waters to mix. After 15 to 20 minutes go ahead and release the fish back into the tank.

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Reader Interactions


  1. rmanpf says:

    Thank you very much- many web sites didnt specify how to clean a small betta fish tank but you have explained it very well.

  2. meldawgal says:

    If you rinse your substrate in hot water you will be killing any beneficial bacteria that are present in your bowl. This is NOT how you should change your water. In fact, you should be doing abouty weekly water changes of about 50%, while ‘hoovering’ or sucking up any waste that has accumulated in the substrate with your siphon. Bacteria are extremely important members of a healthy fish tank, and killing them every week or so is a really bad idea. Both Ammonia and Nitrites will quickly build up and make your betta very uncomfortable.

  3. sec5 says:

    meldawgal, your wrong for a few reasons.
    1. the size of the aqua system will not be enough to sustain beneficial bacteria that would remove waste products from the water. infact the bacteria/algae/microorganisms that _does_ grow will compete with your fish for oxygen and produce wastes themselves. not all bacteria are good.
    2. changing water daily will get rid of of the waste products much more efficiently than using a filter (not enough surface area for the real nitrogen fixing bacteria cultures to grow). in normal bigger aquariums, you actually need a few weeks for the aquarium to cycle for the bacteria to establish itself during which its harmful for fish to live in. so what your effectively doing to your betta is poisoning it.
    3. so killing the (nasty) bacteria is beneficial for the fish due to the small aqua system in consideration. and rinsing it in hot water is a good idea.

  4. Anonymous says:

    I REALLY NEEDED THAT! No other website has told what to do about a small tank. I had no idea, considering i just got my own betta a tad while ago.

  5. Anonymous says:

    Can I make homemade fish food with carrots…ect?

  6. Anonymous says:

    “Can I make homemade fish food with carrots…ect?”
    I’m not sure about for other fish, but for Bettas, they are meat eaters, only feed them shrimp, worms, Betta pellets etc. Food that is only high in protein

  7. Anonymous says:

    bettas thrive off fats rather than carbohydrates like us humans do

  8. Anonymous says:

    how often do you change 100% of the water in 2 gallon tank?

  9. Anonymous says:

    Great site! I had goldfish and WCMM’s before, but the tank was too small for them all really, especially the goldfish so I sold them to someone with a very big aquarium.
    I’ve always liked Betta’s though and I’m interested in getting some fish again so maybe I’ll just get 1 betta for my tank (which is currently going to waste). I’ve got experience now that I din’t have when I started with fish so I should be alright with a Betta.

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