okay, so now im confused. im really sorry. so i should pick between Aphyosemion australe, striatum, or cal?

yes!
Nothing to be confused about. Pick one and do some research.
BigC

okay sorry, thank you so much for your help. i will probably pick the striatum or australe.

okay, well i have decided to get the australe. i have some questions about them though.

-how many should i keep (the tank is going to be a species tank witha shoal of corydoras habrosus, tank is 20 gallons) and what should the male to female ratio be?
-what should the temp. be?
-do the have any special requirements like a densely planted aquarium? (which i think they do)
-are they easy to find in a fish store? i know my local lfs doesnt usually get any killis but if i asked them to order some, would it be difficult?

thanks

See pinned topic at top of section.

thanks

If a killifish is available in your local shop it is probably ok. 99% of the time, the rare and difficult stuff is only available through other breeders.

The easy stuff that can be bred en masse, and kept alive by wholesalers will be all that is generally available

I suggest striatum. Great looking, stays small, not too fussy, and in a well planted, and well fed tank, will probably breed anyway!