Aussiefishy, I'd love to come into your store and take a look at your ritteri. I've kept one for three years now. Definitely my favourite species.
It is unfortunate they get so large. I have more than I can handle with the one I have right now.
The "rules" with this species is, as much light as possible, as much current as possible, and plenty of food. I agree with the already-suggested mysis. Other things, small chopped up pieces of shrimp, maybe some fish (silversides? not too much though), basically seafood.
Now. If yours is eating (and keeping down the food it is offered), this is a good sign. He is sitting on the glass though, because he is looking for a spot with more current and/or more light. Instinctly, they move upwards if they are not getting enough of what they're looking for. In the wild, you will find these anemones at the very top of the reef.
The best way to keep them from wandering is to make a pillar (or "bommie") of rocks and have the anemone sit on top. This will mimic it's natural environment. For current, maybe aim two powerheads at each other, have the point where the currents converge/meet just slightly adjacent to the anemone. This will create some great laminar flow. You want the point of convergence to be slightly adjacent because we don't want to aim the powerheads right at the anemone (powerhead output is an unnatural flow type). If possible, have a source of light directly above. Halides are best.
I know it would be annoying to have it attach to a rock, but, ... well two things. One, it will look better. Someone will likely buy it more easily. You can either sell the rock with it (this is what I'd do, actually). Or, if you use a smooth surfaced rock, you might be able to tease the anemone off. This has both advantages and disadvantages. A smooth surfaced rock is what he'd likely be attached to in the wild. A smooth surface will be easier to coax him off. But, coaxing an anemone off a rock is never fun, and if rushed, can lead to injury of the foot. So, it's a judgment call I suppose. I know if it was me, I'd just try to sell it with the rock.
Take this all as free advice. I don't know the first thing about running a store, and I'm pretty sure I couldn't do it myself. I do know, however, a small bit about anemones and I'm happy to offer to any advice to anyone who wants to listen to me.
