Its a goner. Some might disagree but I think they are tough to acclimate if the params are way off from what they were used to especially a small piece like that and Im not talking about lighting. They just don't tolerate it like some other corals do. If your phos is high and ur No3 is low you're gonna have major issues with torch coral and other euphyllia. For example, I started a new system a year ago and shortly after the cycle purchased (2) torch corals at a convention because the price was very low compared to the outrageous prices torches go for at LFS. One of those pieces died in the first 48 hours, the other survived although it looked shriveled for months until my nitrates got up. As nitrates increased, the look of the coral got better and better. If your phosphates are over .1 which maybe the aren't but from the looks of it maybe they are, this along with perhaps a rough acclimation has slowly killed the coral. Happens, no big deal, test the water and figure it out and try again.