Welcome to Fishlore, Camacho

I have several JD's myself. I keep mine with convicts, jewels, and RTS.
I saw in your profile you're babysitting two? How long is that going to last? 3 JD's in a 55g is going to backfire as they get older. I wouldn't recommend more than two, and even that is pushing it if they're really active. They really need plenty of swimming space.
I've found that when I feed mine live food, they tend to show better color. However, it's best to breed your own live food so you know they're not carrying diseases. Convicts and livebearers work great for that.
I'm not sure if they're compatible with tiger barbs or not. I'll let another member answer that.