Rainbow monti has a spot

[LionsLife_]

Started as a dark spot with polyps closed within the dark area, now looks like this. Any ideas? My gut says it's some kind of stn but I'm not sure.

Should i Break off the effected area and just keep it moving? Everything else in tank is growing beautifully. All tank maintenance is up to date.

 

[biophilia]

I had this exact thing happen about two weeks ago to my seasons greetings montipora. It happened a day or two after shifting my lights around a bit and I think may have been the result of a hot spot from the lights or change in PAR on that spot, but that's just a guess. I did nothing (other than running a variety of water tests to make sure nothing was off) and the dark spot returned to normal coloration after about a week.

Might be worth checking your magnesium levels. Montis are often the first to start losing color if magnesium dips too low. I've gotten the best color keeping mine in the 1400+ppm range but have seen lots of tanks with nice monti coloration in the 1300s too so who knows.

 

[Daniel Waters]

I'd leave it alone and watch it. I have had chalices and montis that will get a spot every once in a while and they usually heal up fine on their own. It could have been from a fish nip, piece of sand settling on it, or just a general sign of stress. This is assuming you haven't made light changes and have proper flow (i.e. not blasting it directly). If you've made recent light changes, I'd be more concerned that it's a negative reaction to the light intensity.

 

[LionsLife_]

I'd leave it alone and watch it. I have had chalices and montis that will get a spot every once in a while and they usually heal up fine on their own. It could have been from a fish nip, piece of sand settling on it, or just a general sign of stress. This is assuming you haven't made light changes and have proper flow (i.e. not blasting it directly). If you've made recent light changes, I'd be more concerned that it's a negative reaction to the light intensity.

Great points guys, Thanks for the quick input. I'll drop the par a little for a week or so and see if that helps. I was thinking it may be a light issue but was such a distinct spot and seemed the rest of the coral was fine I kindve wrote it off. I will definitely check my mag levels as well. Can't hurt to know where you're at. Thanks again