So I've been taking care of gold fish for around 2 years/ 2 generations and think I am ready to redo my settup and get tropical fish. Tetras (neon) seem like a nice intro to tropical fish, and I was also going to mix them with guppies and maybe mollies. Also I DO plan on planting the aquarium. The reason I am redoing the aquarium is that it is an old salt water tank that was free from my dad's friend and gold fish make that annoying oil that I am worried that it may harm tropical fish.. The gold fish have been fine in it but I think it would be good to replace it. Good plan? I'm planning on getting guppies and neon tetras after my last gold fish "goes". I plan on redoing the entire aquarium as it may harm tropical fish because of the gold fish oils and that it is really old and was originally a salt water tank. I already have a plan for basic stuff like planting live stuff for them and simple needs. (Heater, filter, sand, etc). Any tips? I plan to keep the old setup for when they breed as I think free fish would be great.