Weird mandarin behavior

[nolen1503]

Last night my boyfriend looked at the tank about 2 am. He saw the mandarin floating on the surface, in a 'fetal' position, being buffeted by the surface water flow. He thought it was dead. This morning, it seemed fine and has been eating all day (it's a full time job eating 8000+ copepods a day). Is this known behavior or do I need to worry about my mandarin, or both?

Thanks,
Fran

[nolen1503]

I forgot to give my tank info:
125 gal, RO/DI water, Sump, refugium; blue, actinic, and mh lights; Ca 500, KH 10, Mg 1400, NH3/PO4/NO3 0, corals: acropora, montipora, ricordia, acans, zoas, stylophora, gsp, frogspawn, leathers; fish: black ice clowns, Helfrich firefish, chromis, yellowtail blue damselfish, mandarin, copperband butterfly, blue neon goby; inverts: glass shrimp, scarlet cleaner shrimp; CUC: astrea snails, stomatella snails, hermit crabs, emerald crab