You've gotten some great advice.
I haven't found them to be particularly brutal to each other, but maybe that's because I've had them together since collecting them as fry in Uruguay. I have mine (5) including 2 that seem to be a pair in a 2'x2'x1' tank with a little sand, flowerpots, plastic plants, sponge and box filters. They get weekly 1/3-1/2 water change and are big eaters (NLS, flake, red wigglers, whatever). They're in with a chanchito and some Ameca splendens goodeids. Mine haven't spawned yet but could any day (largest are ~4-5")
(Villa) Constitucion is in Northwest Uruguay so is warmer than Southern Uruguay. We found the fry in about 2' of water, overgrown with plants...and crawling with baby wolf fish (Hoplias) and tetras. The larger ones are found with pikes (crenicichla), Gymnogeos, Pimelodella type cats, etc.
Some pictures of Villa Constitucion, Uruguay and my fish...
Matt