Hello, I am currently taking down my tank and starting over. I need to put my small melanurus and 2 clown fish somewhere while I do this. This means they will be there for 2-3 months possibly. I have a tank laying around that is I believe 20 gallons but I'm not quite sure. It's about 2 feet long. Would those fish do fine in that size tank for 3 months with a overpowered canister filter or do I really have to find a bigger tank. Please let me know, thank you.