the foxface is going to bully the copperband...i can almost guarrantee it in a 58 G tank...and your bioload is going ot be large
however that is not what you are asking....
What TCU said works-----here are the methods i used...i had my CBB for 2 years until 2 days ago when he decided to take a swim into the Tunze
I used all foods...squid, cyclopeeze, fresh freshwater mussels, clam, krill, bloodworms, brine, form 1 and 2, form 2 flake, cyclopeeze flake....none of these worked....i soaked all of them for an hour in Seachem Garlic Guard, Zoe and Selcon...none worked....alot of people say the fresh mussel training works and i believe it but get freshwater if at all possible to avoid parasites...
how i did it after all that failed...lo and behold...2 things....live brine shrimp(couple of minutes in RO to get rid of parasites) he ate this but you dont want to do it over a long run....it wont sustain him long at all
and PISCENE ENERGETICS MYSIS(ALL OTHER MYSIS ARE PRETENDERS) this has 69% protein and is FRESHWATER very healthy.....i enriched with garlic and zoe(once they eat a few times drop the garlic it fouls your tank)
what you can do is introduce live brine to get a FEEDING RESPONSE...once the fish has that response and starts eating the live brine...introduce the PISCENE ENERGETICS MYSIS(i mean THIS BRAND, others wont sustain over long run either) enriched to associate that feeding response you get from the live brine and over a few times he will nail the mysis and love it if not on the first try.....
after he starts eating...feed the hell out of him for a few days to get him nourished and used to EATING(keep that response in the back of his brain!!!!!!!!!!!!!!!)
I swear this WILL work...but keep up with weekly WC's because you are going to foul your water in this process...good luck keeping up with that bioload as you have it(you will be fine if no SPS) drop the garlic after initiating the eating and the response is engrained...
KEEP UP AND SUPPLEMENT/ ENRICH HIS FOOD WITH SELCON OR ZOE EVERY TIME THIS REALLY HELPS HIS COLORATION AND DURABILITY UNDER STRESS
THEY LOVE CLEANER SHRIMP BY THE WAY
THE CBB IS VERY FINICKY, TIMID AND EASILY INTIMIDATED BY OTHER FISH LIKE FOXFACE,,,, BE WARY THEY HAVE SIMILAR ATTRIBUTES AND THE FOXFACE IS LIKELY TO BULLY HIM INTO A CORNER IN WHICH CASE HE WILL NOT EVER EAT
-i sustained my Cbb 2 years before the powerhead incident just on enriched every time PISCENE ENERGETICS MYSIS (i emphasize this)
ALSO YOU ENHANCE YOUR SUCCESS CHANCES AND EXTEND HIS VIABILITY WITH A LOADED FISHLESS REFUGIUM----he will receive mysis and amphipods from this alone to supplement the frozen foods...i think this contributed greatly to my success and many others with the CBB
also...you can get mussels at nice grocery stores like Fresh Markey, Whole Foods.....premium food stores...kroger might have it but yada yada
finally and very imporatantly----the CBB gets stressed very easily....moving him around from tank to tank will cause problems getting him to eat...they also dont like confined quarters like a 20 G...i would AXE the idea of a QT feeding tank as i think it has the possibility to hinder your success....put him in the display and teach him to eat in the display---REMEMBER THAT NEUROLOGICAL FEEDING RESPONSE.....ASSOCIATION....EATING ....AND THE ENVIRONMENT HE IS IN..you need to get that ASSOCIATON
I HOPE THIS LONG WINDED ADVICE HELPS