Yep - that huge mouth is to help them grab at passing fish without having to chase them down and get noticed themselves. They will eat just about anything, though. I am keeping them with two angels, a cory cat, and will probably add a black ghost knife fish (always wanted one) to the mix pretty soon. It's a 30gallon tank, so with only 6 fish and a bajillion ghost shrimp (food), it should work out great. I like all the weird stuff.