Marble cat deformity?

[RandellC]

I was really excited to buy a Leiarius marmoratus a couple days ago. The seller lived some distance from me so we met about halfway in a Speedway parking lot. The marble cat is ~16" so it was in a plastic Rubbermaid-type container.

From the top everything looks fine...

From the top everything looks fine.

After we move it to my container and I pay for it, he tells me that it has a red bump under it's mouth. I'm thinking, 'No problem. It's probably just a sore or callous from rubbing the glass.' Then when I get it home and can look at it from the side I see this:

Now I'm like, 'WHAT THE DEUCE!?'

These grainy pictures don't really even show how gross it is. Do anyone know what it is? I'm assuming it's a birth/genetic defect that is incurable. Needless to say, I'm a little disappointed...

[Silurus]

It looks like the gill arch elements of the floor of the mouth cannot be depressed properly when the mouth is closed. It's not a deformity per se, but something that I've seen infrequently in catfishes.
I'm not sure what would the cause be, though. Frequent water changes might help.