Marbled, Mandarin, and Violet are all great, the marbled is impressive even if lazy. I used to get freinds to hand feed mine earthworms, it would just lie there until they got a couple of inches away and the "glomp" it would have 1/2 their hand in it's mouth.
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I think it was because they've been watching the electric blues go after them for a month or so. Hopefully they'll keep it up when I move them off to their own tank (they're getting to big to stay with the lil cichlids). I actually jumped up and yelled at my boyfriend to come look quick.....to bad I failed to notice he was outside 