They belong in a species only tank, they will (try to) eat anything they can, even up to a bit bigger than themselves, and then usually die due to a slow metabolism. I'm not sure if there's the link for the video in the above mentioned link but there's a video of one eating a sailfin tankg without much problem.
Make sure you get a healthy specimen and your parameters are on check, I got a really nice one from DD awhile back, looked great, my parameters were spot on, didn't transfer him out of water (If they gasp during the transfer from bag to tank they can get air inside of their stomach and cause buoyancy issues, also if you feed to much and the food starts to break down in their GI track gas can be produced also causing buoyancy issues), and fed him a good diet.
A couple days after getting him he was swimming around and active, which I just thought he was stressed out due to being in a new home and everything, turned black (which can be a thing, don't buy an angler on their colour as they change as they feel like it/their surroundings), and I just figured my tank is darker the sand is black, he was just blending in. Ultimately he died. Still not sure why, could have just been SAD (sudden angler death) but still it sucks. I want to get another one down the road, but right now still bummed about it so not sure.
There are people who have kept them successfully don't get me wrong, but they just require special attention.
