I just ran into an issue when I bought a chocolate oranda and wanted to mix him in with my betta. Things went well but I then found out through the forum that goldfish and bettas require different water temps. So I brough the goldfish back and learned an important lesson...plan ahead when buying a new fish!!! I then found out that i was not the only one to make this mistake and that many people have different fish in the same tank, each needing their own special conditions met. I have a very imprtant piece of advice to all newcomers to fish...when you get your tank and equiptment, plan and know in advance what type of aquarium you want. Tropical, saltwater, or cool water? This will help you buy fish that need that specific condition and ensure that your new pets are happy and healthy!