I have some fish that I was going to put in a friends 75G setup which currently has no fish. 2 Firemouths about 3-4" and 2 juvenile salvini's (2-3"). I believe the FM's are male but can't sex the salvini's yet. The tank is 4' long with lots of cobblestones. Is the tank large enough to house 2 FM's and 2 Salvinis long term. Will the Salvini's pick on the FM's. Currently the FM's are larger than the salvini's and was hoping that may keep the aggression down. Does it sound like a good CA biotope aquarium?