I had a copperband for 3 years. He ate my home made mix of selcon, amino acids, freeze dried mysis, costco: Frozen scallops, tuna, and shrimp. All ground down while frozen and then mixed and packed together. I had my copperband eating out of my hand everyday. Until my Creole Anthia decided he wanted to eat out of my hand and the CBB stopped coming up for food, he pecked at rocks and would occassionally eat the food that floated by him.
I just lost him over thanks giving, I had him right at the 3 year mark. I don't now why other than the Creole anthia got so big and dominant for food that the CBB just lost his playfulness and got too stressed. It was sad! the CBBs are so smart and will play with you if you interact with them!
I had gotten one for my Aitasia as well. It was that or tear down my tank. Every rock, and my entire sand bed as well as my glass were covered in aiptasia in a 340 gallon display. It was tens of thousands of aiptasia. Within 6 months of having the CBB I couldn't find a single aiptasia anywhere in the tank. It was so weird, because it was slow at first. I thought they were thinning out, but wasn't sure, then all of a sudden I noticed a couple rocks with no aiptasia and had to look back at pictures to realize an entire swath had been cleared out. The aiptasia on the sand bed slowly and gradually disappeared too.
CBBs are voracious eaters! Tons of pods and supplemental food for them is needed to keep them healthy. However, they do well as long as they are hunting for food. Mine never stopped hunting. So, I honestly don't know what killed mine. My parameters were a bit high too. Nitrates hitting between 40-50. So, I don't know if it was water quality, a combination of increasing agression from one or two other fish, or he hit his life expectancy for a CBB in captivity.