Had a large 12" common with rbp and worked fine. Also kept tetras and danios in here with no casualities, but there was a specific method. Anything in the tank before I added rbp were like grandfathered in. Anything I added after the piranhas was dinner including another pleco I tried to add. Thought my big rhom would be ok with a big 8" mango pleco... Bad idea ended up as a 200 dollar dinner that night