I wouldn't worry about it as long as he is swimming and eating fine. It's freaky at first. I had a 3' zebra moray that had an 'off' day once and I almost fainted at seeing my prize black and white eel looking like a prize grey and white eel. He recovered from it within a few hours, guess the crayfish he got for dinner gave him indigestion.LOL
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55gal,260 watt PC(2x65 actinic,2x65 10k daylight,8 lunar LED) 45#LR, 45#LS, 3 maxi-jet 900's on a natural wavemaker timer,phosban reactor, 5 gal fuge (built out of standard 10 gallon tank) with chaeto, grape, and feather caulerpa, sealife systems protein skimmer, wet/dry, 4 blue/green chromi, 1 skunk cleaner shrimp, 2 lyretail anthias, 1 royal gramma,1 true perc 5 mexican turbo snails, assorted dwarf blue leg hermits, astrea snails, and nerite snails | 
