Rio Tapajos Biotope...

Dear Friends,
I am planning for a Rio Tapajos blackwaer biotope wih Geophagus Red Head Tapajos and lemon tetra.It would be very kind of you if you can list some other inhabitants of the biotope for I strictly want it to be of the same biotope......

Thanx for all these info guys..But it isn't Rio Tapajos that I am going to do...well it had been a bad week for me.The new 120gal tank that I bought from my friend had cracked.So have to continue with my 55 gal tank atleast for 6 months till I get enough money to buy a brand new tank..In the mean while didn't get hold of any geos.But surprisingly saw some juvenile balzaniis out here in one hobbyists house.He had kept them at 27 degree centigrade and they are also breeding.The male was huge and about 7 inches.So without any haste paid him a handsome amount for 3 juveniles.1 male and two females.I hope I can raise them for they are used to the hot climate of I ndia.What other species from paraguay can I keep along with these gymnogeos.Please advice me.