Any hope of persuading a CBB to take non-mysis foods?

[RD]

Ok, gotcha, thanks for clearing that up. Even still, if he does take the odd pellet, and that pellet suddenly has a softer perhaps more natural texture/feel to it, AND it's suddenly more palatable due to being soaked in mysis juice (something that this fish does seem to relish), you just might be able to eventually persuade him that it's worth swallowing.
Or not ..... but IMO it's worth a shot.

Good luck, and keep us posted.