I have a 4' long 90G containing 8" Oscar, 8" Pleco, a female Salvini 4-5" a male firemouth about 4-5" and a male Jack Dempsey about 4-5". The tank has a lot of cobblestone rock piles for caves and driftwood. The salvini and JD have been fighting a little bit but nothing serious. Now when the JD and Sal are fighting the FM tries to help out the Sal. I know the FM is male and the sal is female. Could they be a pair? I do not see them digging any pits or anything but they seem to hang out a bit. Could they FM just be trying to make an ally in the tank for its own survival?