I have 8 fish in a 1 yr old reef tank. 7 of them are doing great. There are 2 clownfish. One of them has always seemed to struggle to stay up in the water column. I got both clownfish at the same time. They were very young, less than 1 inch. From day 1, the little guy spent all of his time in the back corner of the tank, resting on the sandbed at the corner. Whenever he swims, it looks like he is struggling to stay buoyant; seemingly always sinking. A couple weeks ago he took occupancy of a bubble tip anemone. The BTA seems to help him rest with a safe, comfy spot, somewhat easier which I am thankful for. His female partner has more than doubled his size. After 1 year, he hasn't grown much. He always has an appetite and eats well. I wonder what is wrong with him. Swim bladder issue?