Mainly it due to the way they are caught, usually by cyanide... So they are normally not in good condition, cyanide poisoning which led to internal infection which is mostly difficult to save... This might also be the reason why they dun feed readily due to the internal infection...
So far, only the Black Leopard Wrasse, Bipartitus Leopard Wrasse and Ornate Leopard Wrasse have some survival rate...
Not sure about Choati but it seems like have quite good survival rate from what I see...