Cichlid tank size?

Okay, so you can pretty much assume I know next to nothing about cichlids. I have been researching them a bit and have come across information that varies greatly. I'm talking about the ones that generally get 4-7 inches in length here, none of the big guys. I've heard from a few people that you can fit 5 or 6 of them into a 30 gallon with no problems whatsoever, but then I've heard from just as many people that they need a minimum of 55-75 gallons or bigger. I'm not planning on starting up a cichlid tank anytime soon, but I figure it's better to do research now than a week before I put fish in.

--Luke

Forgive me; my LFS is the only place I've seen cichlids in person and the ones they've got (other than the occasional tiger oscar or JD) are all in one tank and labelled as "assorted African cichlids" with a maximum length of 6 inches. They are primarily yellow, white, or grew with black stripes over the tops of them. I tried to find what type they were earlier, but I couldn't quite do it. I'll ask an employee next time I'm there.

Okay, after a bit more research I'm seeing just how limited I am with cichlids, but I am definitely open to dwarf species! I'm assuming I can only keep one species of shell-dwellers in a 30 gallon, but I'm uncertain if anything else can go with it. The Neolamprologus brichardi caught my eye-- happen to know how many of them would be happy in a 30? And then could I add some rummy-nose tetras with them, an ADF, small cory cats, or what? At this point I'm really just looking for suggestions and appreciate any help!

I like the look of them! But yeah, the fact that it'd be a species only tank turns me away just a little bit. I do have to face the fact that 30 gallons isn't very big, though. Do you think I could squeeze some loaches or 1-2 otocinclus in with them, and how many do you think would be fine in a 30? My guess would be 3-5, but that's pretty much a shot in the dark.

All right, noted. After thinking about it more I really like the idea of this fish. How many of them do you think would be happy in a 30? And will the tank need to be planted/decorated heavily? Will I need a sand substrate or will smooth gravel be fine? So many questions...would I need 300GPH+ filtration?