Is this STN or pest damage?

[maoiwowie]

Thanks for your help here...The following is a photo of an SPS ive had for 2 years. It has survived through a lot from ALK swings to dinos. Pretty much bullet proof or so I thought. Its been slowly receding at the base for months now.

Can anyone with real experience opine if this can be damage from pests? Does it look like pest damage? I cant see anything that would lead me to believe it is AEFW.

1)I havent added anything for over a year.
2)The damage is slow and actually will stop at times.
3)No other SPS exhibits this damage. In fact all my other SPS are flourishing. Excellent day and night PE with nice visual growth. My colors are vibrant as well.
4) I cant see any AEFW.
5) From the top this coral looks amazing!

I have been keeping SPS tanks for over 10 years now and will admit that im still perplexed by STN and what causes it. I dont think it is isolated to just things we can control like parameters. My parameters are spot on and i dont intend to adjust ALK or anything else. My tank is doing too well to change anything to save this piece. Im not going to frag it either. I want to ask some of the more advanced/experienced SPS keepers to admit... simply stated... sometimes there is nothing we can do.

 

[trinhgiaphu]

i think it's not RTN may be acropora eating brown crab or eating turbo nail

 

[maoiwowie]

I know its not RTN... this damage has occurred over months. No acro crabs that I have seen in the 2.5 years this tank has been running. Im sure there are some sort of snail that eats acro, but surprised i cant find them anywhere. I do have over 30 other acro species not affected.

 

[karsseboom]

To find out if it has aefw take a turkey baster and blast the corals hard and watch for any thing to fly off it. The other thing you can do is dip the coral and turkey baste it while dipping and watch if any flat worms come off. Aefw are very very hard to spot sometimes, look for tiny red eggs or bite marks. That does look like a smooth skin acro and we all know how much aefw love them.

 

[defchild84]

i think it's not RTN may be acropora eating brown crab or eating turbo nail

acro eating turbo snail? oh man that's scary lol.

I am no expert, nor have I had a decade of sps experience. However.... in my humble opinion, it would be hard to rule out the lighting/shading factor. Not knowing where your fixture/retrofit sits and lights, it is difficult to pinpoint a definite answer... but definitely worth NOT ruling out. Capricornis are notorious for this, as well as many other corals, which begin to STN on shaded areas has a large 'stn'd ' base. IF, you wish to keep the colony "as is" , which I would too, and would like to rule out a few possibilities, as ugly as it would be, I would recommend super-gluing where the live flesh meets the dead to prevent further death. If it is heavily shades, I'm sure the death will sloooowly continue- if they are pests, I'm sure the death, or the stn will occur rather quickly, and in areas possibly not close to the area super-glued.

 

[maoiwowie]

Looked for bite marks and eggs, found none. Tried the baster but nothing flew off either. Ill keep this up for a few days. The shading factor is a consideration, this piece sits almost directly under a 250MH. If indeed the shading is the reason, what are the factors? Why some acros over others?