I have 3 Trilins myself. I have kept them for almost 18 months now, so I must be doing something right...
I feed them mainly one tablet of Tetra Tabimin per day. I pop it in the tank when I feed the other fish 5 mins before lights off, by the time it has dissolved the lights go off and only the TriLins find them (as they feed mainly in the dark at night I believe).
Once or twice a week I'll chuck in some Daphina or bloodworms: Alot in one go because by doing this it overwhelms the mid & top feeders allowing some of that to fall to the bottom where the TriLins can then have their share. When feeding flake, they have not learnt to go to the top like the rest of the fish, but will take it if stumbling on a flake or two left on the bottom.
Andy