Oh! I have a 12g killifish tank! I just adore them

! I have Fundulopanchax Gardneri killifish (they originate in W. Africa) - aka Clausen's Steel-Blue.
Here is a picture:

There are many different kinds - my fish encylcopaedia lists 20 alone! But, there are even more varieties... some require brackish water and some can tolerate freshwater (F. Gardneri) so it is important to checkl out the requirements for different kinds of killifish first. SOme are very easy to care and others and are very hard! A good place to find out more about them is at the American killisfish Association:
http://aka.org/modules/tinycontent3/There is a Beginners Guide, a forum (although not very busy, sadly), lots great links, and lists of events and chapter meetings if you want some fish or eggs.
I purposefully chose killis becuase I had never really had tropical fish before but I also did not want Danios or Tetras, which are nice fish but I wanted something different!

These guys are a lot of fun and I am really happy with my chioce as they have endured several of my inexperienced mistakes!