Nice pictures so far everyone!
None of my tanks are true biotopes (yet; hope to get there some day) but are nature-inspired aquariums with a geographic theme.
Here is a setup I had last year; south American river tank with crenicichla sp. Venezuela, redhook and black bar myleus
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And another which has been taken down, central American stream/pond tank with panamius panamensis, hericthys tamasopoensis, ameca splendens, and belonesox belizanus
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currently working on the Mexican river tank I've posted elsewhere on the forum. When it evolves a bit I will post it here.