Would the following tropical freshwater set up be suitable for South American Puffers? 84 Litre/18 UK gallon, dimensions: 60w x 35d x38h. Quite heavily 'live' planted top to bottom with bog wood and larger stones creating many hiding places. The substrate base layer is 1.5 inches of Laterite/4mm natural gravel mix - with another 1.5 inch layer of the gravel only over the top. How many SA Puffers could this tank comfortably hold allowing for future growth? What about the male to female ratio? I've heard its a bad idea to have other fish with Puffers but ideally I'd like a couple of bottom feeders to help with cleaning (or shrimp/snails but I've been told they'll get eaten!).