I got this basic idea from a betta post I saw and just adapted it to what you see below.

I recently set my old 55g up again for Angelfish Fry. Since I will have several different sized spawns at a time, I wanted to section it off...so I needed two tank dividers.

The store brands have a few major problems:
1) They're ridiculously expensive for the dollar or two of plastic they're made of.
2) They don't really fit very well.
(Gaps between the divider & glass)
3) If you're using it for fry, they can easily pass through the gaps.

I used a very cheap and durable plastic mesh product called "Plastic Canvas." It's used for needlepoint. You can find it at any hobby store. It's basically just a big sheet of plastic mesh. The holes are small enough to allow water flow - and keep all but the smallest fry in.

Before I show you the step-by-step, I want to mention something. I siliconed my pieces into place. Since I'm going to be keeping fry in a bare-bottom, I had to. The smallest gaps will let fry in and out of the sections. If you want to divide a tank for larger fish, you can just use suction cups to hold these in place - making this an even easier DIY project. So here we go...

No making fun of my dirty old 55. I cleaned it up nice after this.

All you need for this project is one or two sheets of plastic canvas (99 cents each), a tube of silicone or some suction cups (another couple dollars), and some scissors.


My plan was to divide this tank into three sections. One divider in the middle - making a 24 inch section on the left, and two one foot long sections on the right side.


First I cut the height so it was just under the black top plastic rim of the tank...


Then I trimmed the canvas to the proper depth. I folded the edges over a bit until the depth was right - then trimmed it on the folds. If you were using suction cups instead of silicone, you'd leave those folded flaps instead of trimming them and just make one hole per suction cup big enough to fit the end of the cup through.


Double-check and re-trim the deoth until it is a nice snug fit.


Run a nice, even line of silicone along the canvas in the front, in the back, and along the bottom. Smooth each line down with your finger...ensuring there are no gaps between the glass and the mesh.


Here's mine half-way done...just the center divider.


And all done - with one 24 inch section and two 12 inch sections...


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Yup! I have used these, too!

Remember to allow the silicone to fully cure before adding water. The smell from the silicone will be gone when it's cured.