Here's a little info from WWM on 'shrooms:
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Hi all,
<Steven & Anthony answering in tag team fashion.>
I believe I read in CMA that healthy mushrooms can live for "months" without feeding. Also something like it would be good to "spray food in their direction"....but what do they EAT? Where can I get it? Does it have a drive through? Wes
<Generally, mushrooms feed heavily, but primarily through the absorption of dissolved organics with a little feeding on small creatures. There are some mushrooms, namely the Elephant Ears, Amplexidiscus & Rhodactis, that are capable of eating large fish. Steven Pro>
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What to feed, or if it is necessary at all to feed is going to depend on what type of 'shrooms you have. Best to figure out what you have, post the name, then we can figure out what they need from there. Zoanthids and paly's are the same way...some will visibly eat when target feeding, and others will not. If you are unsure of how to determine what you have, posting a picture would be most helpful. As far as the zoas and paly's I have *that feed*...they love rotifers and cyclopeeze - some of the larger paly's will actually catch and eat mysis. You'll want to use something to target feed (turkey baster works ok), and gently swoosh the food over the colony (food mixed with SW from the tank). If you squirt too hard, the polyps will just close up w/o eating.
If it's easy to shut off your powerheads while feeding, I would recommend doing so...it just ensures that more of the food ends up in the desired place rather than all over your tank (especially noting that you don't have a large clean-up crew at this point to take care of leftovers). You won't have to feed them much, so be careful here, and once to twice a week should be plenty.

As far as light, the mushrooms seem to prefer lower light, and the zoas and palys are pretty flexible.

Wendy