Thanks cedric, justin and terryz for the encouragement. Anyway, this is the last time i try PBrT already since already have a PBT in tank and doing well. Was hoping they both settle well and that's it for our livestock. Sometime things are just not meant to be.
Nitro, yeah, we did consider putting in Refrigum.. what we did is that since the PBrT was not feeding when we bought it (we knew it as it's from CF and they don't feed the fish as they mainly exports) so we quarantine in our QT for about 1 week. After 1 week, we decided to try and put in betta box to see if he may eat when we feed other fishes in main tank.. sadly no.
Actually, when he was released into the main tank, he was still quite ok. He was chased around a little by the PBT and the forever aggressive YT but he seems to hold up well... Ultimately, if he don't eat, really nothing much we can do... haiz..
Anyway, just keep our fingers crossed and see if miracle happens.