^indeed
We do have info on their care just the outside sources selling these animals (liveaquaria for example) is misleading and causes abunch of questionable information against the true information.
Linkcias eat the "biological film algae"... it is the ONLY thing they eat which we can get them to live off of.. On the note of them eating sponges.. they DO eat sponges.. but only one or two species which we cannot identify.. it would be a hitchhiking sponge, we know that, so the sponge diet is something we just ignore as it isn't going to keep it alive and we have no clue which sponges to feed... kinda the same case with certain nudibranches.
In a large tank, assuming 100 gallons.., and more than a year old.. preferably two.. the film will hopefully have spread enough for it to live off of. Any sooner and they do starve. No promises they won't run out eventually and starve anyway.
They are very VERY senstive to slight traces of nitrates.. phosphates.. and anything they has a minor swing in water quality such as salinity or PH.
They're very prone to parasites. Most notable is a type of snail which can be seen and plucked off the star before any deep wounds occur causing infection killing it.
All starfish in general cannot be exposed to air.. this is a rather argueable subject as we don't know why and coastal stars are constantly in the tides.. but lets be on the safe side and just stick with it anyway.
Fromia stars (red tile, marble, red fromia, etc..) are very similar in their dietary needs.. just less prone to disease and parasites and stay smaller.
I have had a blue linkia in my 90 for about a year now. I have personally seen them attacking and eating asternia star fish. Actually, last night, after lights out I did my usual before bed check and the linkia was on the front glass eating an asternia. I grabbed my camera. lit the scene with a flashlight and snapped a couple of pictures. I haven't had a change to take them off the memory card yet but I will post them when I get them downloaded.
As for being very sensitive to even slight traces of nitrate, I'm not sure where you are getting your information from, since you said there is not much information on them, but I have been battling nitrates for some time now, above 20ppm and up to 35 ppm and the star is just fine. I am currently dosing vodka to try to bring those number down and also just started cycling a sulfur reactor because while the inhabitants of my reef are surviving and even growing, I know they would be happier with lower nitrate levels.
Cannot be exposed to air: Mine will occasionally move to the top of the tank and put itself in a position where one and sometimes even two arms are out of the water.
At one point, several months ago, it developed a small ulceration on one of its legs rather close to its body. I was worried that I might lose it. It took several weeks, but the sore completely healed and now there is no trace of it.
Here are a couple of recent pics:
stars by
rworegon, on Flickr
star in zoas by
rworegon, on Flickr
it seems to like grazing through zoanthids. I'm not sure what it might be doing except that I have seen asternia stars attached to zoa polyps. Maybe its eating them.
The linkia is one of my favorite animals in my reef. While I wouldn't encourage anyone with a brand new tank to go out and get one, I don't necessarily agree with the paranoia surrounding them and the "leave them in the ocean" mentality.