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How to Make a Cheap Homemade Betta Tank Divider

Marie is a lover of everything about and inside of aquariums. Among other friendly creatures, she has a turtle that she adores.


Fish Tank Divider

If you plan to keep two male betta fish in the same tank, you better have a divider to separate the two; otherwise, fins will be torn to shreds.

The benefit of having two males share an aquarium vs. giving each a separate tank is that it simplifies care. There is no need to buy two heaters. There is no need to add dechlorinating formula twice. There is also no need to worry about where to place the second tank. It’s all in one, minus décor and food—those you will have to do twice.

The downside of having a divided tank is that there will always be a risk of one fish getting loose. This is why foolproofing the divider is so important.

Store-Bought vs. Homemade Dividers

PetSmart and other pet stores carry screen tank dividers; the cheapest is $9.99, and that’s for a 10-gallon tank. For most people, that size is enough. But many have complained that it doesn’t fit right, warping because it is coiled in the box. Many people end up having to cut and modify it because the dimensions don’t match the tank.

Why spend $10 for a coiled mesh screen that you have to cut to make fit when you can buy flat plastic mesh and suction cups separately for $6?

Supply List

Here is what you need:

  • Plastic Mesh Sheets (I know Walmart sells packs, but Michaels sells individuals for 60–90 cents each)
  • Suction Cups (a few bucks for a pack of four—you may need two packs)
  • Two Feet of Fishing Line (surely you know someone who fishes)
  • Poster Boarders (long black plastic things you clip around the edges of a poster individually, near the poster section at Walmart for few bucks)
  • Scissors
  • Tank

How to Make the Divider

I highly recommend you put this together in a dry, barren tank. It would be no fun trying to create this with water abstracting your view.

There are several ways to make this tank divider. One way is to make a one-sheet divider like the ones they sell in stores. However, I think the more space you put between the fish, the better. So I will go over what I did for my tank, making a double-sheet betta divider.

  • For a 20-gallon long tank, you’ll only need two sheets.
  • For a 10-gallon tank, you might still need two just in case.
  • For a 20-gallon tall tank, you will need to buy at least one more sheet, two to be safe.

Step 1: Measure and Cut

So you got all of your materials. Time to start measuring and cutting your mesh. Because the poster boarders are going to clamp the sides of each (to make it sturdy), keep in mind that there will be an extra centimeter or two for the plastic boarders. Constantly check by adding the poster boarders after every cut and place it in your tank. I accidentally made mine too short, but I will go over how to correct this later.

Step 2: Secure the Mesh With Suction Cups

So you got your mesh sheet with clamped poster boarders. You’ll want about an inch between the sheets, so it helps to measure and mark the top and bottom part of your aquarium (you could mark it over tape) so you know exactly where you want your sheets to be. In my example, I used eight suction cups with four on each side. I lined up the cups, making sure each sheet has a top and bottom cup attached with fishing line. This is the difficult part, because if you make the line too short, the poster boarder will be over the suction cup, creating a gap and possibly a warped sheet.

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Step 3: Fix Any Concerns Once It’s Created

So your finished product looks a lot like mine. The suction cups are pressing against the sides, creating gaps between the cups, or you simply cut it half an inch too short. If you think there is a possibility that your fish could get through, then they can. But don’t worry; I have a few solutions.

  • For one, if the gap isn’t too large, measure and cut up a piece of plastic straw and simply squeeze it between like I have done.
  • If the gaps are too wide and the pieces of straw loosen and float up, use any remaining mesh and simply tie it outside of the sheet (like I have also done). Don’t tie it on the inside, because the fish will be able to press through it. By tying it outside, there's no way they can push through. Make sure it's tied as close to the original mesh as possible; you don't want it to be loose.
  • Adding gravel and leaning heavy décor against it will also keep it secure. For the sake of lowering the visibility of the other fish, add some unused aquarium plants between the mesh.

Enjoy Your New Divider

That’s it. Just make sure there is no way for one of your fish to get through to the other side. Once you have built it and made necessary alterations, keep an eye on the tank for a while. One of your fish might find a way, and you want to catch the mistake sooner than later.

When doing water changes, you’ll want the water level to at least be 1.5 inches lower than the top of the mesh. Remember, bettas can jump. Enjoy!


© 2013 mariekbloch


Korin on September 20, 2015:

works for my 5 gallon tank with 2 betta fish i live the idea even two years later THANK you

mariekbloch (author) on March 27, 2013:

Thank you. It was fun to make.

prasetio30 from malang-indonesia on March 26, 2013:

Very inspiring hub. I love your tips and I can't wait to make it soon. Thanks for writing and share with us. Voted up!


mariekbloch (author) on March 25, 2013:

I am aware that I have two heaters in the picture. They're both really weak and they barely keep the temp. right, so I use them both. Planning on getting a bigger heater.

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