Stick to fairly low numbers and chose fish that use different areas of the tank
Bottom: 8-10 Pygmy Cories (Corydora habrosus or C. pygmaeus)
2-3 Nerite Snails
Middle (numbers will depend on species): Tetras (bear in mind embers, neons, cardinals etc will all hide low in the tank) so maybe Silver Tips, Penguins, Red Eyes etc
Pencil Fish (Beckfords Pencilfish or Hockey Pencilfish aka nanostomus eques)
Small Rainbowfish such as Forktail Rainbows (popondetta furcata) or any similar species, threadfin rainbows etc
Any of the harlequins (normal, copperline, hengeli or purple)
Top (numbers will depend on species): Microrasbora, Microdevario or Boraras species of dwarf rasbora.
Marble Hatchetfish
Algae Eaters : (the previously mentioned snails)
Otocinclus x 4
Just some ideas
and remember you will have to keep an eye on compatability between those species
I also wouldn't go too mad planting tank out, its so dee you will struggle.
If it were me, this is maybe what I would do (I kept this tank as a marine so mainentance in mind too...) ....
I would have coarse sand at the base with some pebbles (
http
/www.unipacpet.co.uk/aquatic/aquarium-sand/ - Fiji Coarse or Fiji Fine as they are ok with corys but don't show up dirt as much as beach type sand and it looks natural) with a few natural rocks or cobbles (not too big to lift out because deep tank = easily dropped or hard to reach) and some Sumatran Driftwood (
http/www.unipacpet.co.uk/aquatic/driftwood/) using a few nice tall bits to build height into the tank without plants and using cobbles to stop them slipping.
Might even go for a few Anubias or Java Fern plants attatched higher up to the wood for shelter and colour!.
Then fish wise I would personally have (build up over a year or two after cycling):
Bottom:
8 x Corydoras Habrosus
3 x Zebra Nerite Snails/Pink Ramshorn Snails.
3 x Otocinclus (I would go for O. cocama the Zebra otos but they are expensive!)
8 x Black Crystal Shrimp (would go for high a grade as possible, even if meant starting with only 4 and leave them to it, they will go through filter and will breed like rabbits, if you are smart and find the right LFS to deal with or online or on our forums, can sell the offspring! Higher the grade the better the price and in the long run you might be able to get back your tank cost lol)
Middle:
10 x Pentazona Barbs
Middle/Top:
6 x Popondetta furcata (forktail rainbows, 2:4)
4 x Marble Hatchets
(was going with 10-15 microrasbora but remembered the strainers for the filter, they would get sucked through on that tank!)
Might after a year and a half/two years if all is established and ok, add a pair of Yellow Honey Gouramis or likely a pair of Croaking Gouramis as a feature fish. Im not all for tacky colourful inbred fish as I cant be dealing with all the health problems likely to occur but its a case of each to their own, instead of small rainbows and hatchets, you could go for 6 colourful male guppies for top/middle.
As for regular maintenance, I personally found algae was really hard to get in the corners of this tank so you do everything to prevent it growing in the first place. So few things I found helpful:
*RO water is so much easier for keeping tank clean than tap water! I changed 1 x 25L barrel a week which worked out perfectly!
*Wouldn't plant anything other than either anubias or java fern due to depth and light and the sideways flow of water.
*To help prevent algae and without plants etc... I purchased some Rowaphos and used it right from the start in the first chamber with heater.
*Buy some plastic (floating) biomedia and put in in the second from last chamber where the protein skimmer would have been for improved capacity for breaking down ammonia.
