[Delphinus]

You mentioned that you've fed it already. My guess is, it's expelling waste.

But, being that it's only 2 or 3 days into your tank, it is still very much a sensitive period. The first bit after purchase is usually a rough go of it.

I would feed, but feed only moderately for the first bit. If it is stressed and has depressed metabolism, it might not be able to digest food faster than the food will decompose, which can lead to infection.

Water motion, currents, and surface agitation are important for the long-term survival. Make sure there is enough current to carry away any wastes, you don't want that sitting lingering on the tissue.

Do you have other anemones in the tank? Did you sell your ritteri or do you still have it in your tank?

Time will tell if it's just expelling waste (it shouldn't be like that for long, perhaps a half day or so), or if it's something more sinister at play here.

Dissolved O2 levels are very important for anemones and particularly after shipping it's very important. So do make sure there is adequate surface agitation. There are those who actually recommend using a powerhead venturi or an airpump/airstone as an "emergency first aid for anemones" and it's probably worthwhile considering this for the first few days after purchase. I mention this because it's an option I'd keep open if you don't get soon get a "warm and fuzzy" feeling about this.

Carpets seem to fare quite badly at first. Once they've settled and adapted to life in captivity they can be fairly hardy. But it's that first little while where it's very much touch-and-go. I don't want to sound alarmist but the statistics are not very good. Be careful and good luck.

Hope this helps..