Will these tankmates be good/ok together-

Tank is approximately 56 gallons. Taller tank, not like a normal 55 or anything like that.

1 Red Tailed Shark
6 Barbs
6 Oto's

Tank is well filtered.
Fluval 305 Canister (I think it's a 305)
also a hang on tank biowheel

Instead of the Otos-
Maybe a small school of Cory's and a Clown Pleco?

The Red Tail Shark and the Barbs shouldn't bug each other much I assume.

I read they are 'mostly' aggressive to their own species. I know all fish have individual temperaments though.
My tank has a large piece of driftwood, and I will put half a ceramic flower pot in it so the fish are welcome to hide and stuff.

I have never owned a red-tailed shark, so I have no experience in their behavior.
I would plan on getting everything around the same time, so they can all grow up together. I have found that 'sometimes' helps a bit. They don't feel as threatened as when new tankmates are put in it seems.