UPDATE
 

My copperband loves the fresh oyster and mussles. He and the niger trigger finish it off in no time and the copperband gets a huge belly then. So with a diet of live white worms daily, PE mysis (which he only eats a few) and fresh shelfish every 2 days, he's fat and happy.

Interesting to see how the copperband push away the trigger when he comes near the oyster at first, then leave the place for the trigger. Good thing my niger trigger is a big pussy and not aggressive at all and wait until the copperband leave. In fact it is the niger trigger that showed the copperband that the thing in the shell was food! it is only after seing the trigger eating it that the copperband went for it.

I notice my CBB stays active at night and seems never sleep.
It that why they don't live long?

no :) they don't live long sometimes because they are cought with cyanide and this slowly attack their liver and kidney and eventualy one of both organs fail. Copperband butterfly prefer lower light and they usualy hunt after the lights are out, especialy if there are moonlights. This is why I bought mine actualy, to eat the nasty amphipods that come out after dark and eat all my zoanthids.

If the copperband has not be poisoned by cyanide and its liver and kidney are good, it is well fed and eating well and fat, then it should live many years. I know someone how had one for nearly 7 years.

Many people think that their copperband is healthy but they are skinny with no fat pad at the top of the head and top of the body. They should be thick there. They should not be pinched at all but rather the opposite.

The guy where I bought my copperband from said the fish was eating like a pig. It was eating 3 to 4 PE mysis per day and that's what he called eating like a pig. The fish was very skinny and emanciated. Juging from my experience with mine, copperband butterfly eat A LOT! wow...almost as much as a trigger.

I tried fresh oyster as you suggested and he likes it.
it is the only thing my CBB eats beside mysis.
I will try some live white worms later.

Glad to hear it's working. Once it get used to the oyster, try fresh mussel. Mine love both. Of course I am pretty sure he'll love live white worms. The mussels are much cheaper than oysters and mussel have less fat and more protein, so I consider this some of the best food for a nutrition value. I will try to keep mine on mussel as base food, with about 30% white worms in the diet.

White worms must be given in small quantity as too much fat food may lead to fat liver disease. They are fat and a rich food so once the copperband has gained back its normal weight, it is a good idea to limit the quantity of fat food.

I am now giving mine about 20 to 40 white worms per day when I am not feeding oyster, and less when feeding oyster. Copperband seem to ONLY love fat rich food. PE mysis is very rich in fat, oyster as well and of course white worms. Maybe their instinc drive them to this type of food, not sure. I would love to know the dietary value of their natural diet which is mostly worms.

Here are the nutrition facts about fresh mussels:

http://nutritiondata.self.com/facts/...roducts/4186/2

and fresh oysters:

http://nutritiondata.self.com/facts/...roducts/4189/2