Hey there, I'm sure you've done your research but maybe should take a look at this: http://bettacare101.com/mythvsreality5/ If you put them in the same tank it should only be for when they are ready to breed but in between breeding they should be kept separate. Trade me is a good place to look, Using search terms: Betta, Fighter, Siamese in the fish section There is less on there than usual at the moment but they come and go. http://www.trademe.co.nz/Members/Listings.aspx?member=1814549#ListView_CardRepeater_ctl01_card_GeneralCard_listingTitle http://www.trademe.co.nz/pets-animals/fish/fish/tropical-fish/auction-989738799.htm