Hi witheraf:
The following info is not from my experience but ideas of Peter Hiscock in his 2003 book "Encyclopedia of Aquatic Plants".
In his proposed set up entitled "An Indonesian stream" (pp.114-115) he suggests using a 48"Lx18"Wx18"H tank. I quote:
"In the rain forests of Indonesia there are many small tropical streams, often slow moving and swamplike, with overhanging vegetation creating light and dark patches. A number of aquatic plants flourish in the iron-rich reddish substrate, which is interspersed with small pebbles and stones. Many of the species for this biotope are slow growing and do not require strong light, making this biotope an ideal one for beginners to attempt. However not all the plants from this region will do well without strong lighting. Many are found in areas with little overhanging vegetation, where intense sunlight penetrates the shallow waters.
The red substrate often found in these types of stream is the result of iron, and can be recreated using a reddish brown gravel. Water quality should be neutral to soft (pH 6.8-7.2) with a temperature of 77-80F (25-27C). Provide additional CO2."
As this book is about plants, the info is focused on them. However, Hiscock offers a list of suitable fish (considering the plants he proposed).
"Suitable fish: Many aquarium fish come from the Indonesian region, including some loaches, anabantoids (gouramis), and barbs. Bottom-dwellers for this aquarium include clown, horse-face and kuhli loaches, and algae eaters, such as the flying fox. For midwater swimmers, try tiger, checkered, five-banded or cherry barbs, and dwarf, harlequin, or scissortail rasboras. Some gouramis are also suitble and will do well in the hiding places provided by the plants and bamboo. Suitable anabantoids include Siamese fighting fish, three spot, opaline and gold gouramis, pearl or chocolate gourami, paradise fish, and the kissing gourami."
I would comment that both Clown and Horseface Loaches usually will outgrow a 48" tank so I would stay with the small sized loaches. Also that a Kissing Gourami could become a threat to other fish.
As back-ground plants he suggest using the following: Blixa echinosperma (Giant Japanese Rush); Hygrophila corymbosa "crispa", Rotalla wallichii (Whorly rotala) and Rotalla rotundifolia.
For the mid-ground: Microsorium pteropus (Java Fern) and Vesicularia dubyana (Java Moss), both attached to
driftwood (he placed the driftwood towards the right end of the tank).
For the fore-ground: Cryptocoryne affinis, Cryptocoryne balansae, and Cryptocoryne moehlmannii (Moehlmann's Cryptocoryne).
As for
aquascaping, Hiscock uses Bamboo canes and bogwood placed across the tank.
Now from my experience:
I keep both community and species only tanks of fish from this region of the world. The fish I love keeping as main fish are Rainbowfish (Glossolepis incisus, Melanotaenia boesemani, Melanotaenia lacustris, Melanotaenia splendida splendida).
I'll stay with two of these tanks for sharing my experience, both are Perfecto 30Breeder (30"Lx18"Wx13"H):
As bottom dwellers I have a Rainbow Shark in one tank and a school of Upside-Down Catfish in another.
Mid-Swimmers: None in one of them, a school of Glass Catfish in the other.
Surface-Swimmers: None in one tank, small
betta sorority in the other.
I use
DIY CO2 at the moment in one of those tanks. With around 4" thick substrate mix of natural river sand and Eco-Complete (or alike). I recently upgraded lighting in order to keep some light demanding plants. I kept those tanks in low light for six to eight months and they looked great.
Keeping a heavily planted tank as this ones is time demanding but highly rewarding. During the first six months I performed almost weekly (skipped a week here and there) 30-40% water changes; now I can do either a 25%
water change every other week or a 10-15% water change weekly and the parameters stay quite close to ideal for me. I use extra filtration in one of the tanks but low-end filtration in another (on purpose).
Pepetj
Santo Domingo
Similar Aquarium Fish Forum Threads 
It sounds like a wonderful tank!
