Yellow tang anus injury or something else?

[foxt]

I have had this yellow tang in my system for over a year. It's a 220g mixed reef that's been up about three years, with about 20 different fish, the largest being a kole tang (about 2x the size of the YT), and a bluethroat trigger again about 2x the size of the YT. The rest of the population is made up of several different wrasse species, two clowns, a foxface, and I am probably forgetting something, but nothing aggressive. They all get along. There are also a few emerald crabs, hermits, snails, in the system. As far as I know, I don't have any predator crustaceans, things have been doing well for quite some time.

Found the YT dead this morning, quite a surprise. It's been eating well, showed no signs of distress yesterday. The only visible sign of something wrong is what appears to be either a wound or some sort of infection around it's anus. It seems unlikely that it is an injury or wound inflicted by something else in the tank, but what else could it be? There aren't any signs of anything else on the corpse. Any thoughts on what might have caused this? Here are the pics:

 

[Zionas]

What have you been feeding the Yellow Tang? Have you noticed anything else aggressive towards it?

 

[Big G]

Sorry for your loss. It may have been suffering from Rectal Prolapse. The rectum protrudes outward and the fish is often unable to defecate. Internal infections (the redness you see) begin which can lead to death. So with this "soft" material protruding, it makes for an easy meal for crabs, and others.

 

[Zionas]

Are Yellow Tangs or any other fish commonly imported with this condition?

 

[foxt]

Thanks guys.

Are Yellow Tangs or any other fish commonly imported with this condition?

Not that I know of.

It may have been suffering from Rectal Prolapse.

This little guy appeared to be doing well, and I did not notice any external signs of a prolapse. I have to admit that I had not been especially looking for this, so it's possible. Although I do think I recall actually seeing the YT poop normally within th elast week or so (haven't been staring enough at the tank this last week or so). A prolapse could explain it, but I am wondering, how long does something like that take to develop? And would it have an effect on other behavior? The fish seemed to be behaving normally yesterday, and was eating well.

What have you been feeding the Yellow Tang? Have you noticed anything else aggressive towards it?

I broadcast feed reef frenzy once a day, and add a sheet of nori along with it. The YT was grazing on the rocks and the nori, but with the kole tang and the foxface also doing the same, I don't know how much any individual picks off the rocks.