I picked up a freshwater dwarf puffer from Organism driving through Christchurch the other day and currently it is in a bare cycled 27L aquarium. I would like to turn this tank into a biotope aquarium and am going to be using a JBL plant substrate with burnt Sienna gravel on top to replicate the red, iron rich substrate from their natural environment. I am unsure on what plants to use and still need to purchase a lighthood (anyone got a small one to sell?) so if anyone can give me some ideas on what to do that would be great. I might do something with the excess narrow lead java fern in my community tank and might purchase some Cryptocoryne. Any general tips on dwarf puffers would also be greatly appreciated.

you'll want to put hiding places in there asap or it'll get stressed out

Yeah I put a heap of Indian fern in there for now and a spare coconut cave.

Dwarfpuffer.com has a great list of plants for a dwarf puffer native biotope. There are also some good articles of people going out and getting them from the indian rivers.

I would like to turn this tank into a biotope aquarium and am going to be using a JBL plant substrate with burnt Sienna gravel on top to replicate the red, iron rich substrate from their natural environment.

JBL Manado is a lot more red than that Burnt Sienna stuff and it is also porous so bacteria can colonise it, plus it absorbs and stores nutrients and releases them when the plants need them, so much better than Burnt Sienna IMO. It is roughly about $30-$35 for a 5L bag, so not too expensive either.

Too late. I'm using JBL aquabasis plus underneath the burnt sienna which also absorbed and stores nutrients when they have been depleted. I did look into manado but prefer the look of the burnt sienna.