Preparing a Rio Negro Biotope

Hi!
I will join to the AGA 2009 in the biotope category,so i want to create a 'true' biotope of Rio Negro.I have 3mm black gravel(brown mixed) and lots of driftwoods.For the plants,can i use Heteranthera zosterifolia(stargrass) and Cabomba caroliniana?And i want to use Echinodorus sp. too but which species can we find in Rio Negro?For the fishes,Bushymouth catfish,Cardinal tetra and Hemigrammus bleheri and i want to have a dwarf cichlid too but which species?For the foreground plant can i use Echinodorus tenellus?
Sorry for too many questions and my bad english.

Thanks.
My tank is 80*40*45cm,145lt.I searched Negro ecosystem on fishbase and i found only Apistogramma wapisana,no ram or bolivian ram.I thougt that these fishes were living in the blackwater rivers but i found nothing.What about the plant selection?I'm not sure for the echinodorus sp. too.Are there all species in that area?This link says too that there are the dwarfs bu when i click on Rio Negro there is no dwarf cichlid!

I don't think.For this category,the rules are too strict.Ex:If i create a south american biotope,it's not a true biotope,it's only a geographical theme.Do you have any idea on another biotope(for south america).

Thanks a lot!I solved the plant problem and for the fishes i will go with rummynoses,cardinals and bushymouths.

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