One of my 6 year old large Goldfish (10" long+) started to look like he had swallowed a tennis ball. This was unusual, as he was a "normal" fish to begin with. He progressed to the size of a baseball, and was getting bigger by the day. He lost many scales and started to get red striations on his skin. After he died, I did a necropsy and found that he was filled with an orangy yellow almost clear gelatinous material. The color and density was consistent throughout. His white bladder was small in comparison to anther Goldfish I had necropsied. Could someone explain to me what I was looking at? I realize that there are numerous forms of tumors, but this was ubelievable and was growing at an alarming rate. The rest of the fish in that pond seem to be healthy.