Is this Duncan being eaten or just receding?

Robert Binz · Jan 20, 2021

Attached are photos of my duncan coral. I’ve had him for about 5 months and he’s weathered many storms in the tank.

AFTER adding an emerald crab I began seeing this tissue loss. I thought it was from a nutrient issue but after the loss continued, I examined him out of the tank and saw this irregular tissue loss with islands of issue separated from the rest.

This looks to me like he’s being snacked on. The emerald crab lives below the duncan.

There are no finish in the tank and I haven’t been feeding the emerald because there’s plenty of GHA (although he doesn’t seem to be eating it).

My question for y’all is whether it (1) looks like something is eating the duncan; (2) looks like receding tissue from underlying problem; or (3) can’t tell from the image / need more information.

I marked this emergency because if the crab is probably eating the duncan, I want the crab out ASAP

Dkmoo · Jan 20, 2021

Look up brown jelly disease. Looks like that to me. Crab picking at it would look more localized to me and they usually don't pick on corals unless coral is already dead or dying or if its starving.

Robert Binz · Jan 20, 2021

Dkmoo said:
Look up brown jelly disease. Looks like that to me. Crab picking at it would look more localized to me and they usually don't pick on corals unless coral is already dead or dying or if its starving.

Would BJD be a problem when this is the only coral impacted and I haven’t added any new corals in half a year?