well you guys are gonna thuink im crazy, but i currently have 2 bgks in the same tank along with 2 brown knives and 2 glass knives....when i first got the second one, they hated eachother, but now they actually sleep on the same side of the tank, often within a few inches of one another...they are awesome fish, but i wouldnt recoment putting them with any of the bigger bichirs, or clown knives, or aros... they seem to do well with my angels ,congos ,discuses,ropefish and even my eels... haha i even have a couple newts in there with them