I have a hexagon 21.6 litre tank for a betta fish. I wanted 3 of the small albino cories for the bottom. They can go with Bettas so that's all good but is thee tank size too small?
They can get quite big Marie, i wouldnt consider anything other than Pygmy corys for a tank that size. They are super cute too! and you could probably have 6 of them. The betta really shouldnt pay them any interest at all.
If so, then i would not recommend 3 of these in a tank. minimum group size should be 6 for any cory, they like the company of their own kind and should be kept in bigger tanks with good flow as they like to play in the water current.
Thats why i suggested Pygmy's
Being so small, you can have more numbers, thus happy fish.
However, with all that said, i still dont think i would put any corys in a tank that size.
No, a hex of this volume will have a small foot print, it's unsuitable for most species, though C.pygmeus, C.habrosus and C.hastatus should all be fine.