Your tank is just a little over 40Gallons. The Bristlenose will get 5-6 inches long and each of the Tetras and Danios will get 1-2 inches long. so it will need to be something small. Maybe a Dwarf Gourami? How nippy are the pristellas? If their not a Betta would be pretty in there. Just some thoughts.
I wouldn't put a Betta in there...only tetras I'd trust with one are Black Neons, Cardinals, and maybe Glowlights. And I have mixed feelings about Bettas with Danios...
Um, Zebra Danios get bigger than 1-2 inches...like 2.5-3 inches from everything I've read. Pristella Tetras I would guess are 2 inches.
4 Bristlenoses...20-25 in
6 Danios...15-18 in
10 tetras...20 in
.................55+ in total
So it sounds like you're overstocked...in other words, don't get anything more, in fact I would recommend removing a few of the fish, maybe a Bristlenose and a few tetras.