I’ve successfully had tiger barbs in with neons tetras before in a 40g breeder tank, however the swimming space is greater in a 40 than a 55(which I currently have now)anyway I’d not recommend that as tiger barbs remind me of wolves or lions of the fish world. They don’t always chase other fish, usually they just chase eachother but Once in a great while they did bust up a pack of neons and then chase a lone running neon, no neon was lost but the barbs seemed to never give up sometimes even though the neons were much faster.. They travel and harass in packs and when just one fish decides to set their sights on another fish they all follow suit..it made the tank nice to the eye to watch them chasing eachother and darting around the obstacles as they are a VERY active fish from my experience...Someone with more experience can help you better with your current stocking situation. However currently my 55 gallon has a pleco, 10 or 11 neons, 2 small angel fish I had to rehome that May stay permanently unless they get nipped or until they’re big enough to eat my neons, a mixed group of 10 or 11 platys, 2 velvet swordtails,5 red minor tetras and they all get along and the tank is fairly interesting to watch during day.. Im currently lightly dosing with prime and stability until my bacteria catches up due to the swords, red minors, and 4 platys being new, I personally like some of the guppies ESP the sunrise guppies and Dalmatian mollies however I’ve never had them. I’ll try to remember to get a photo at feeding time so the new fish come out and you can see what they all look like together.