Receding prism coral growth patterns

[aflux]

I've got a reverse prism that's been doing great, but I just noticed this one little spot of tissue that's started to recede. Everything else in the tank is thriving, no issues whatsoever. I'm stumped as to why this is happening. Has anyone else dealt with something like this? I'll post my parameters tomorrow. This coral has been in the tank for about 3 months and was growing like a champ until now.

[aflux]

Still stumped.

[Korvu1]

I'd consider checking your lighting and flow levels, see if they're too intense for that particular area. Also, do you have other favias in the tank that might be giving you a clue?

[Kaledon7]

Something nearby might've stung it, I'd try a dip and see about moving it to lower light, flow might be a bit much too.

[angelwras]

Appears to be a sting or damaged area. I'm thinking, what other tank inhabitants could've caused this? What's your fish and CUC list look like?

[aflux]

I dipped the coral as suggested and now I've got a new area of recession on the prism. Moved it to a new location in the tank too. Still stumped though - this coral's slowly receding around the edges and I just can't figure out why. One thing I did notice is it's got a slight algae on it, which is weird since it's not showing up anywhere else in the tank.

[aflux]

Appears to be a sting or damaged area. I'm thinking, what other tank inhabitants could've caused this? What's your fish and CUC list look like?

My tank inhabitants include a Blue Hippo Tang, Scopas Tang, and a Lieutenant Tang. I also have a small school of Pajama Cardinals, three Orange Lined Cardinals, and a pair of Lyretail Anthias. A Tail Spot Blenny rounds out the fish population. For cleanup, I've got a Cleaner Shrimp, a handful of Blue Leg Hermits, and a few Astraea Snails.

[aflux]

Still stumped about this receding issue, so any additional thoughts or suggestions would be great.

[oceanflux]

Consider a few possibilities: a tang might be nipping at the coral. Take a step back, observe the tank for a bit, and see if you notice anything unusual. Another option is pests - try checking the reef at night, about an hour after the lights go out, for crabs or large worms. Lastly, it's also possible this is just a natural occurrence, in which case there may not be much you can do about it.

[fluxable]

Just wondering if you ever figured out what was causing the recession on your favia, I've got one that's experiencing something similar.