terror in my tank

[reefhawk]

Hope some one can help me. Something is terrorizing my tank at night. When I turn of my m/h and leave on the moon lights my fish are in complete terror. Woke up three mornings ago and my lawnmower blenny was killed and partly eaten. Thought maybe all my hair algae is gone he didn't get his share of nori and maybe starved or died of old age or something. Hate to lose a fish but everything else seemed ok. Next morning i look and my midas blenny is missing half his tail and sone flesh at the base and he is spooked. Close examination turns out my largest fish - a foxface has a wound on his forhead. I stayed up half the night watching for something to show its ugly face but i see nothing. Get up this morning and my foxfaces tail has a hunk out of it. havent added anything to my tank in quite a while. Only thing different in there is my clowns have finally moved into their anenome. Maybe a crab got big or a mantis shrimp? Anyone have a similar experience and figure it out?