No help here but my Yellow Choris is the strongest swimming fish in my tank. Gorgeous as you have seen but no other fish can catch it. Buries itself in the sand at night to sleep.
Posting a picture would be most helpful!
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Currently tankless.
20 Gallon mini reef with mated pair of Maroon Clowns given to Rougiem!
80 gallon reef given to Rougiem/Wooster HS.