Hey Vu,
They are notoriously difficult to get eating. i know you QT your fish as it is, which is good. You will have to work hard at the feeding to start. Try the basics, but also look at frozen Cyclopeeze, Arctipods, etc...
I would also keep some LR in the QT for them to pick on unless you find you have to treat for any treatment. The fact that you got it from LA will help with all of the above problems, so hopefully a non issue.
<--Bobby