I was given a "defective" acf, missing both front legs. Initially it lived in a 50g with dwarf africans and assorted fish. Until it grew large enough to become a threat to the other inhabitants. It was then move to live with medium to large goldfish. Until one day, I found that the ACF had bitten an eye off of a black moore goldfish. Admittedly, goldfish are not know for brains. The frog was again moved into a 30g with 6 african knives, heavily planted with lots of caves. This combination appears to work well, both eating frozen blood worms and staying our of each other's way. Although I don't think that they would "hunt" for a fish, if one gets too close.... I have also seen a ACF, simply sitting on the botton of a 90g tank, a feeder goldfish swimming by to escape an oscar bumped into the hand of the ACF, and just that fast the goldfish was swallowed. Truthfully, I would not trust them, long term, with any fish that could possibly fit into their mouths.