My first post on this site so I hope I'm doing everything okay! I currently have a 34 litre (9 gallons) tank containing ten white cloud minnows, and a single mystery snail. It's been up and running with them for about nine months, no issues whatsoever, not a single death (despite cynically planning my stocking around losing a few). Prior to that I did a fishless cycle, and then took in an already sick betta, which died soon after. Currently all parameters are fine, I do weekly water changes (1/3-1/2 a tank), everyone is happy. But the minnows keep growing, and I realise that a 9 gallon is realistically too small for the next four or so years. So, as a birthday present to myself, I'm hoping to upgrade to a 200 litre tank (a bit over 50 gallons). My question is, what should I house in this larger tank with the minnows? 50 gallons, cold enough for wc, at least 10 wc minnows and a snail. I am considering just a giant school of minnows to be entirely honest, but I know my parents would enjoy some variety and a bit of a show piece. I'm just not sure what would suit given the colder temperatures, and the incompatibility with goldfish. Most of the fish I like are tropical. Would the white clouds mind terribly if I had a heater to raise the temperature just enough for low range tropical fish? Also no fish which would harm the snail either, as he must come over from the 9 gallon. If I can't find any cold water fish, I may have to just give them away and look for tropical fish. A special note, if anyone knows of any Australian native fish which would suit, that would be brilliant. Sorry for the long piece! Thank you.