I have a Venezuelan pike that’s around 13” and 4 it dats with the largest being 11” in my 72x30x25 240g. Other tank mates are a polleni 10-12”, 2 true parrots 10-12”, a small 8” severum, silver dollars and clown loaches. Once in a while the pike will try to stir the pot but everyone stands their ground and nothing happens.