Ive had a biorb 30l for some years now and had lots of heartache and frustration as Ive tried to stock it up to the level I wanted.
Ive tried to get the target 10-12 inches of fish but I can never sustain more than 6-8 fish/inches at any one time. Currently I have 5 rummy nose tetras and one solitary Tiger Barb which have lasted for 18 months so I may have stumbled on the optimum number. Rummynose seem to school a little as well, or at least as much as they can in a Biorb.
Previously had Zebra Danios *much underrated , constantly on the move and the long finned ones look better to me and they are good for a new tank.
Cardinal Tetras did well for while, smaller than the rummynose perhaps so could be worth a try, best get 5-6 as they seem better in a group.
Green tiger barb (I love the look) and the usual orange striped Tiger Barbs but they can chase the other fish, including their kind, around, bit of a pain.
Otocinculus did really well at cleaning the glass and the plants (not a bottom feeder I was told),tried 3 at one time but they died out because I think I tried to get too many fish in the tank.
Plants just dont last, tried twice, I,m nothing if not persistent, now have plastic plants
And I hate that the curvature of the bowl can hide those little fish sometimes.
So I would echo what others have said,if you can send it back, if not try 6-8 fish, smaller tetras/raspboras etc. as suggested (perhaps after you have tried something hardier like 3-4 Danios to start the tank off) and I'd suggest one species to encourage schooling.
Might be worth trying an Otocinculus as well to help with the cleaning.
Let me know if you try a shrimp or two as I'm about to upgrade to 90 or 120L tank and not sure what to do with my Biorb, might be worth trying some shrimp and layering the bottom with pebbles maybe.