I like the idea of doing small biotope-ish tanks. I would only look at doing a pair of dwarf acaras or dwarf eartheaters in a 20 gallon long tank, or a trio of apistogramma or checkerboard cichlids.
I am a big fan of the smaller catfish species, as they come in so many patterns and are found in most of the water ways of northern South America. But I agree with ajbry
, that they do produce an incredible amount of waste, possibly too much for a SA community tank in a 20 gallon long.
I have 8 small panaque catfish in my 150 gallon tank at the moment, and omg do they poo alot. I am doing 30% water changes every 4 days just t keep the nitrate levels under control, not to mention keeping the tank looking clean. A good way see just how much poo they produce, try feeding them some sweet potato.
I think it's a choice between having a single bristlenose and some otocinclus, or having small groups of corydoras and otocinclus. Personally I'd go for the corydoras, becuase of thier social interactions.
Generally when looking to put together a stock list I start with the cichlid profile from FishBase
. Towards the bottom of the page, you'll find a link to Occurrence Records
, this is where I start my search for tank mates.
Next site I visit is mongabay.com
. It has some real good pages, particularly; Biotope Aquaria Ecosystems
and Country Database
. These aren't complete lists, but they are a good starting point.
I also visit PlanetCatfish
and go to the search function and type in the river where my cichlids come from, for example Rio Orinoco
, and find a Cat-e-log
link, go to Habitat Information of the catfish and click on the river to bring up a list of all catfish found there.
Finaly you can always do an advanced google search, such as Rio Orinoco + tetras