My brother got one of the hang on the wall tanks for christmas a couple years ago,meybe longer.(this is wen i had no idea about how to care properly for them) The tank got really dirty real quick. wen i learned a little about bettas i tried a little filter. didnt help at all and it was hard to get it just right so the outflow would flow back into the tank. So i made my brother move the betta to a differnt tank.(cant recall what i moved him to becuz it was a long time ago)
Anyways, in my experience, they are not sutable for bettas or any fish.