coral cat shark rash

[kcrokin]

Hi everybody my name is Kevin and I have a coral cat shark that has a rash that has come back again, it was on her once a few weeks ago and I have overly sufficient filtration on the aquarium, my biggest worry is that half of my substrate is sugar sized sand and the other half is a bigger sized sand, I am afraid that it is causing the rash, I have taken a picture of her belly and it is worse than ever if anyone has any idea on what I can use the help the rash go away or what I can do in my aquarium, it is a 220 and it is just her, I realize that it will be too small when she is an adult, right now she is 13.5 inches long and I have four motors pumping water in all directions and I have a wet dry and a canister filter on there as well as a protein skimmer and even an air pump blowing bubbles in the aquarium your help would be much appreciated.

Thanks again,
Kevin

[Gwynhidwy]

I'm don't have much experience with sharks, but I do know that they require well rounded substrate, so if your larger grain substrate isn't very well rounded I would try to replace it. You might also try asking in the aggressive fish section here on RC and/or contacting a public aquarium that keeps this species.