Iridscent Shark,diseases and remedy

Question
Could u tell me the common diseases that iridscent shark suffer from.I have 2 of them one died due to an abnormal swelling in the tummy area,have no clue of might have happened.The other shark looks ill as well.If u could tell abt diseases and also symptoms with regard to theses kind of shark ,i'll be a great help.

Answer
Hi Chitra, one of my mollies did the same thing. What ended up being wrong was my water levels in my tank were off and the high amount of nitrite was causing my fish to be sick. I would bring a sample of your water to your local pet store and they will tell you which levels are off and give you a supply to fix that. Add aquarium salt to reduce some of the levels in your tank! Good Luck!