IYO what is a good freshwater ray that stays small/ is fairly hardy, and what is the minimum size tank for said ray? i just want to see what different people think
motoro's general are hardiest but females can grow to 36" disc span and will need 8'x4' tank.
hystrix are the smallest rays but can be a bit tricky to feed - think the only grow to 18" (but i may be wrong)