we have had many leporinus over the years. if kept as a single specimen they are fin nippers with slower moving tankmates, but no real issues with tough or fast fish. right now we have one about 7" in a 300 with 4 bigger oscars and a large cat, no problems at all, maybe due to lots of space. we had a group of a dozen once and had no problems with tankmates, but there was always a definite pecking order and the smallest leporinus had few fins left (sort of reminded me of the dynamics in an mbuna tank). lots of driftwood and rockwork for places to stay out of site helped in that setup. also, they seem to love veggies.