Ulcer by Jin_Yu posted Jul 10, 2017 at 9:16 PM Ulcer by Jin_Yu posted Jul 10, 2017 at 9:16 PM Hi all! I'm new here. I am taking care of a friend's 2 iridescent sharks and the 16" albino shark developed a big ulcer on its side over the course of the last 2 days. The owner is out of town, I sent him pictures but he has no idea what it could be. I haven't been able to find any pictures online to help identify what this is. At the beginning it looked like a bump of air under the skin like goldfish get when their bladder is acting up. This morning though, an open sore opened up and it leaking white grains of sand or flesh into the tank (but they float). The fish is large..like 16" long and it shares this massive tank with another black iridescent shark. As you can see, I'm not an expert here but freaking out at the thought of a giant dead fish or that whatever is wrong with this fish will also infect the other fish. Here's some links: Iridescent sharks ulcer Iridescent sharks in their tank Update: Progressed Ulcer (day 3) Any help would be appreciated..