Hello,
If I wanted to assure my barnacle's survival, should I try feeding it??

I've had him for a week in a new tank- he is one of my favorite hitch hikers. He seems to stick his cirri out less now so isn't filtering as much... ?? any ideas?? I'd love to keep him alive.

Do some research on possible foods. The main challenge with filter feeders like barnacles in reef tanks is that often the amount of food they need can lead to nutrient problems. You might try some sort of spot feeding and quickly siphoning excess food.

Thank you. No one really tries to keep barnacles alive so I haven't found much about them. The way he waves his cirri around has given him quite the persona! I'll feel bad if he croaks... thanks again.

ime oyster eggs works well as a food source, as well as frozen cyclopeeze (more specifically, the liquid frozen with the cyclopeeze).

There's also bottled forms of marine snow - it should give you a fair amount of variety in their diet. Siphoning afterwards would help with the excess food, but a large CUC could help too.