gz louise that thing is serious lol. In terms of varied diet, so far im thinking shrimp, silversides and massivore. What else woudl you recommend is good for them?I would feed it a varied diet, and as for tank mates any fish in with it is a risk, a poly will just get eaten, and the oscar is a risk. As is shown by this video they will happily eat fish that are about the same size, and could try to eat larger with less successful results.
PS. In 12h my gulper will be in his tank