How long to leave an oyster in the tank?

[daniella3d]

Today I gave my copperband a fresh oyster. At first it did not toutch it at all and was even afraid of the thing. Then my trigger came along and started eating...then the butterfly took a bite and voila

He's eating slowly and picking often at the oyster so I was wondering how long can I leave it there? Can I put one in the morning and leave it all day for the fish to eat?

It's a fresh oyster so it is alive before slicing it in 2 and putting it in the tank. I rinse it before with tap water. How long do you leave oyster in your tank? does that pollute?

Also how often should I give it? is once a week enough (expensive at 2$ each!)? The copperband only eats live white worms beside the oyster and of course the pods in the tank.