If a critter looks healthy, it's feeding. I hand fed mine, it would close up around the food...then some critters started disappearing (lawnmower blenny, shrimps) then I found my Copperband butterfly in it...it released it because it was too large, but not before it stung it to death, it had angry looking welts all over it. Anything that got too close was either eaten or stung to death, when it got to the size of a dinner plate, it found another place to live out of my tank....never again will I put a beautiful fish killer in my tank.