male bettas together

Question
so i had set up my 16 gallon tank to house my 3 male bettas. my mam had made some dividers for me using plastic canvas and file binder things, (sorry dont know what they are called). well i have a major problem. when i added the bettas the one on the left and the the one in the middle can fit through the small gap thats in the front or back of the tank, depending on whether the top of the file binder is under the lip of the tank at the front or back. i couldnt find a proper tank divider for my tank, which is why i made one. now i need to know what i could use, or what i should do?

i have moved my 2 veiltails back into the 10 gallon and the crowntail is still in the 16 gallon. my mam didnt want my having both of the tanks running, but ive spent loads of money on gravel and plants for the 16 gallon, and i dont want to chuck it all.

thanks for any help

Answer
Hi Sarah, well first of all, its nice to see that your trying to give the Betas more room. I hate seeing them in such confined spaces. I don't really know what the shape or dimensions of your 16 gallon tank. I too had a tank that I put a few beta in. Fortunately, a local franchise pet store sold "dividers" for aquariums, specifically for that purpose. They plastic of course with many small holes throughout it. You could cut it to shape whatever size you needed. It was a few years back, I don't remember the name of the product. I think I purchased it from pet supermarket. Not sure if you have those where you are. Worked great though. Check that out. If you have no luck with that, try your creativeness with plastic cuttingboards. Real thin and easy to cut with scissors. If you decide to do this, make sure you drill many small holes throughout them to keep the water flowing throughout the entire tank. Should work good. Good luck, let me know what you come up with.