Zeke,
Moves too quickly and without any sorts of "tells", but I'll give a video a go and post what I catch. You certainly don't see the mouth snap open/shut- lightning.
These little'uns are living on ostracods/gravel inverts and bits along the glass/sand interface in the full current, and also as partial predators: scales, fins (they love the new guppies), snail eye-stalks etc. Nasty.
Teeth are front-loaded and forward-pointing for a grab, shake & rip (aba/wolf/Chana/flat-head sleeper) rather than a cut (ATF).
I've got 2 now. Had maybe 1/2 dozen in the other tank when I first caught them (months ago) but they succumbed to my stupidity along with everything else in that tank (long story including a frigate bird and a puffer, posted somewhere here). As bunches they seem to get on, though they don't seem to school or socialize per se. They also don't seem to cannibalize even when there's a size disparity, though they shouldn't be trusted, either.
Water conditions would be clean, hard and fast, I'd think. I've only seen them in the full-flow portions of limestone streams. Egg & juv. stages are marine (I think) as most things are around here. A high-flow/river setup for loaches and/or gobies would be good for these guys- they look and move like a butterfly loach and they're about the same size. The only issue is their nasty nature...
I've not seen them eat/attack anything that's not alive, though they've taken interest in bits lionfish and or tinned salmon. They smell the pellets and turn, but don't pay attention beyond that. May try a worm later on.
A
