I heard you need a very well established tank. Not much is known on what they eat , but an established tank will tend to have enough micro fauna of what ever they eat to sustain them. Also I believe its is one linkia per 100 or 200 gallons.
Yeah they are VERY tough to keep bro. Alot of people say its better to leave it in the wild. Though some have kept one in a 500+ gallon aqurium and live for quite some time. Well if I ever hit the super lotto Ill get one LOL!
I have two a blue and a baby blue. Had them for atleast a year probably more. Moved them from or to a minimum of three tanks. They mostly don't survive because they run out of food.