Like many cats it comes down to quite a number of things.
Size of the cat, size of potential prey, size of and aquascape of the accomodation, feeding regime and very importantly the personality of the fish and how it was brought up (with other larger fish, with feeders or solitary) .
All things together give an indication if a cat can (safely) be kept with other tank mates.
Safely - term used until it turns out not to have been safe!