Kissing gouramis are also known as kissing fish or kissers. They are a tropical freshwater fish found from Thailand to Indonesia where they are eaten as food. These cute fish get their name from their unique mouths which are highly protrusible so when they move them it look like they are puckering up to kiss. The "kissing" is an aggressive gesture and males "kiss" while trying to attract females.
(there are fish yaoi fans who knew?) Sometimes they "kiss" another fish (when it's another kissing fish it's adorable) or objects in the tank.
Link to a video of a pair kissing because LJ is being a pain: http://youtube.com/watch?v=k6Jj0TDSlXY
Edit: Added infomation about the "kissing"