Something eating my duncan or is something else going on?

[Calm Blue Ocean]

I've had the coral about 7 months. Noticed this hole about a week and a half ago and it's only getting bigger. There is another around the side developing as well. I haven't noticed anything picking at it. Pictures show progression over 10 days. The duncan is still opening as normal.

 

[Aboynamedsous2]

I've had the coral about 7 months. Noticed this hole about a week and a half ago and it's only getting bigger. There is another around the side developing as well. I haven't noticed anything picking at it. Pictures show progression over 10 days. The duncan is still opening as normal.

What live stock you have?

 

[Gtinnel]

In my experience if there is any livestock in your tank that is eating corals they go for the tasty, fleshy bits on top, not the thin layer of tissue on the skeleton. If it is a pest then I'm not sure how they typically start consuming a corals. I also know that on my lps it's common for them to have exposed skeleton below the head.
When my duncan was being eaten it closed up and stayed that way for a long time, even after the fish had been removed.

 

[Calm Blue Ocean]

In my experience if there is any livestock in your tank that is eating corals they go for the tasty, fleshy bits on top, not the thin layer of tissue on the skeleton. If it is a pest then I'm not sure how they typically start consuming a corals. I also know that on my lps it's common for them to have exposed skeleton below the head.
When my duncan was being eaten it closed up and stayed that way for a long time, even after the fish had been removed.

This is my experience as well. I have a peppermint shrimp who ate polyps off a birdsnest (and when she was doing it there was no missing it because she was quite in love with it). My clowns like to bite random things. But I've never seen any of my fish or CUC go for the boring part of the coral.

 

[Calm Blue Ocean]

What live stock you have?

Fish: Two clownfish, a YWG, a Pink-Streaked Wrasse, a Red-Lined Wrasse, a Midas Blenny
Inverts: Tiger Pistol Shrimp, Two Peppermint Shrimps
CUC: Red-Legged Hermits, a Blue-Legged Hermit, Astraea Snails, Conchs, Cerith Snails, Trochus Snails, Nassarius Snails, Tuxedo Urchin

 

[Aboynamedsous2]

Fish: Two clownfish, a YWG, a Pink-Streaked Wrasse, a Red-Lined Wrasse, a Midas Blenny
Inverts: Tiger Pistol Shrimp, Two Peppermint Shrimps
CUC: Red-Legged Hermits, a Blue-Legged Hermit, Astraea Snails, Conchs, Cerith Snails, Trochus Snails, Nassarius Snails, Tuxedo Urchin

 

[Aboynamedsous2]

I’m not an expert but I do hear people complain about peppermint shrimp a lot.

 

[Calm Blue Ocean]

I’m not an expert but I do hear people complain about peppermint shrimp a lot.

Definitely never trust a peppermint. And I can't 100% say this wasn't her work, but as an avid night watcher, I'd think I would have caught her in the act by now. I'd also think she would have done a lot more damage after 10 days given past experience.

 

[Calm Blue Ocean]

So the hole continues to expand. Still no obvious predator spotted. I'm thinking of trying an iodine based dip in the morning and probably move it to the frag rack for closer observation.

 

[Lost in the Sauce]

So the hole continues to expand. Still no obvious predator spotted. I'm thinking of trying an iodine based dip in the morning and probably move it to the frag rack for closer observation.

Probably a good idea. Any change?

 

[Calm Blue Ocean]

Probably a good idea. Any change?

The hole doesn't seem to be progressing upward (yet) but all the tissue below it is gone and it's joined with the hole on the side. The tissue on the top side is looking healthier, though (knock on wood). The duncan has about 6 heads and all seem happy except the main original one. The "tentacles" on the side of the hole are not fully opening. I've been making a point of target feeding it to see if that might help and it gives me a solid feeding response.

I'm starting to suspect the original cause might have been a snail rubbing past it. They love to park under it during the day and the original hole is about in line with the edge of their shells. Still, if that was it I'm shocked at how it snowballed. The only other thing I thought might have caused it, but this is maybe reaching, is that one of my clowns likes to bite it, oddly enough, on the opposite side of the damage. Even though the "biting" doesn't seem overly aggressive, I'm wondering if he maybe pulled on it hard enough to tear it. It would only take once.

Either way, hopefully things are stabilizing. Thanks for asking!

 

[Lost in the Sauce]

Do I understand right that now, the hole is all the way through the skeleton, or that the tissue loss from one side is now all the way around, connected to the other?

 

[Calm Blue Ocean]

Do I understand right that now, the hole is all the way through the skeleton, or that the tissue loss from one side is now all the way around, connected to the other?

Just tissue loss with the two holes connected around the side. The skeleton is solid and looks undamaged.

 

[Lost in the Sauce]

Just tissue loss with the two holes connected around the side. The skeleton is solid and looks undamaged.

Thinking this through. Not convinced about the snail shell theory but honestly, don't have a better idea. Everything else in the tank is happy. No apparent bacterial issue?

 

[Calm Blue Ocean]

Thinking this through. Not convinced about the snail shell theory but honestly, don't have a better idea. Everything else in the tank is happy. No apparent bacterial issue?

My LPS and softies all seem happy and growing with no obvious issues (toadstools, blastos, zoas, candy canes, sinularia, kenya tree, xenia, gsp, alveopora). I've got a relatively new traumatized monti cap but I think that was me moving it up too high in the tank too quickly.

 

[fishguy242]

hi,possible clown clearing to lay eggs?? does the duncan host them?

 

[Calm Blue Ocean]

hi,possible clown clearing to lay eggs?? does the duncan host them?

I think they might have been considering it as a host and thus the "biting" but they are actually hosted by a rock and although they have yet to spawn they do regularly clear under their rock. The rock is an upgrade from their old host which was a Tunze 9004 skimmer.

 

[Calm Blue Ocean]

Thinking this through. Not convinced about the snail shell theory but honestly, don't have a better idea. Everything else in the tank is happy. No apparent bacterial issue?

I forgot to mention, I did have an AquaBiomics test done last month which found no known pathogens. Actually it found that I didn't really have much of anything good either. For an 11 month old tank it seems my diversity is extremely lacking. Yay for no bad stuff but a bit more good stuff would likely go a long way toward happy healthy corals. Of course that was a few weeks before the duncan started losing tissue so maybe something got introduced after that.

 

[fishguy242]

but tissue recession has stopped now?

 

[Calm Blue Ocean]

but tissue recession has stopped now?

It seems to have stabilized. The edges are looking cleaner rather than lifting and yellowing. I'm being hopeful.