Whats wrong with my Tiger Barb?

sorry for the phone pic

I got this little guy a few weeks ago and he has since taken to eating less and less. Now he mostly just hovers in place twitching rapidly angled at about 45 degrees down. even with food (omega one tropical flakes or veggie tabs) right in front of him he wont eat. any help would be greatly appreciated hes a gorgeous little fish

i try to do water changes once every 5 days, the tank is about 5/8 planted vs synthetic with anubias and an amazon sword, also stocked with 2 gouramis and 6 zebra danios

tank parameters: 20 gal 76 degrees 7 pH 30 Gh 40 Kh <.5 NO2 <10 NO3 ppm mg/L

thanks you for any advice! im a relatively new tankist