I have a large rock of yellow and green rics that I picked up thanks to thelogicalreef. I also have one of those hot pink and orange with blue and green rings ricordia, also courtesy of thelogicalreef.
Nobody paints their ricordia better than bryan. Oh, was I supposed to say that Bryan?
Bleaching is usually a sign of lack of light - very common in cheap store bought anenome's
It may be their color I don't think feeding has anything to do with bleaching. It will definatley affect thier overall colors, but not like bleaching - I am not the expert, but tha MHO
Correct me if I'm wrong but, aren't ricordia not very light-demanding? I always thought that they didn't need intense light. If that is the case, the bleaching might be possible. Try moving the shrooms into a lower light area of the tanka nd see if they recover some of their color.
Generally speaking, yellow ricordea is either dyed or bleaching. There have been several debates about this during the past couple of months. Apparently a lot of ricordea and anemones are coming in dyed yellow or red.
while I have joked about Bryan of thelogicalreef.com painting his zoos and shrooms before selling them, I must say that the ricordia posted are real. I have some real wild colored ricordia in my little reef and one massive colony that is similar to the ones you posted here, both bought thru bryan and they have not lost one drop of color and the large colony has had a few shrooms split and the color is still there.
I have purchased dyed single shrooms in the past: they look like a yolky-lemony yellow. Just keep them where they are: the last one I bought like this turned into a fantastic maroon/green ricordia yuma. Takes about 3-4 months for them to pass the dye out of their system and get their natural zoox going again. very interesting process.
Then again, I'd recommend NOT buying dyed corals if you are aware of it. Check out this RC thread I posted to a year ago of a dyed alevopora: pretty tempting, eh? LFS, too. The photo ended up being used in the following article from reefkeeping online mag's Sept 2002 issue. Good reading:
I used to have orange ricordia just as bright as those in the pic, if not then brighter, and it wasn't died (as it was propogated from another reefer's tank). Also I remember reading if a coral is died then the entire coral is one color, if it has more than one color in it then it can't be died - but I'm not sure on the validity of that statement.