As mentioned, I've had a sunburst Anthias in my 58g reef tank for the last 6 months.
It seems healthy, has great color, and is `out' a good bit; so while my success is quite short-term yet, I guess I'll add what I can about these fish. Given experience like Kevin and others in this forum [see my question above, to the wise folks here] ... I'm sure I might be contradicted, and probably have a lot yet to learn about these fish.
Getting a Sunburst:
These are deeper water fish, and collectors often don't decompress these fish well. Swim-bladder problems are mentioned in almost every guide.
Personally, I got mine from the LFS. They had it for almost two months - swimming and eating well. I wouldn't order one of these online, I'd find one that's been at a LFS for a while, known to be healthy in captivity - and wait until that point to get one.
Otherwise, just unsure how to suggest finding a healthy one.
Tankmates:
I took the Marine Center's advice to heart [that the most aggressive fish these should be housed with is a Fairy Wrasse]. The folks around here that I've know try them never had them last very long [maybe half a year] .... and they were rarely seen in their tanks.
As my most aggressive fish is a Midas Blenny - and I feel at times like my Sunburst feels quite menaced by the MIdas ... they aren't kidding when they say to watch what fish these are housed with. I attribute the amount of mine is out, the health to the fact that I have a fairly low stocked tank with the Midas as the most aggressive tank-mate.
IMO, if you're not guiding the tank stocking around the Sunburst - another fish would be a better choice. Maybe I'm over-opinionated for being under-experienced - but that's my take on these fish and the not-great record many have in aquaria.
But IMO for a tank like ours - the sunburst can be a feature fish, with all other fish smaller/more mellow/compatible with it's needs. In 3', tangs and angels and the like IMO are easy to avoid with a star fish like this one.
Other stuff:
I feed daily, or try to. Sometimes multiple times on the weekend. While the Sunburst is pretty unusual and not tightly related to the other Anthias - but I'd still err on the `feed often, small amounts' like is said for Anthias.
Lighting. I have a number of overhands, caves, and arches that my Anthias loves. Having an `open' rockwork with lots of darker areas, passageways, etc seems to suit the Anthias well. It seems love hanging out at the edges of overhangs - ready to swim out in the water column, but not really `open water swimming'.
If your caves are hidden, if you've got fairly solid rockwork - you might not see it as much.
It also seems to make it happier with my MH lighting. It seems ok with it, but might spend more time swimming around in the water column with just actinics on - I dunno.
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Anyway, I tend to view this fish as best kept as a `feature fish'. A 3' tank like ours might be a good choice [at least until it gets big] as avoiding tangs and other fish that might intimidate the Sunburst are easily avoided and it's not too hard to have a very passive smaller tank.
I would consider all the tank mates, though. I've been thinking for a few weeks about what fish to add to my tank - and am asking on a couple boards to insure the best success I can. These are timid fish, more timid than their size ... and seem like it would be easy to keep stressed and not eating well - a fairly quick death.
Anyway - I'm only at 6 months with mine. At a couple years I'll probably have something useful to say
.... but it's definitely my favorite fish I've kept so far and IMO worth the sacrifices needed to have it thrive.
I'd love to hear others experience with Sunburst - I've got a lot left to learn
[and if you can advise on my tank-mates question above, I'd love it!]