1.5 ft long 5 gallon Suggestions

Wow, there certainly has been a lot of interest lately in 5 gallon tanks. I just set one up and I think about three other people are exploring the idea.

Here is my set-up:
5.5 gallon
AquaClear Mini filter
25 watt heater
14 watt fluorescent lighting
onyx sand (big money)
anacharis
java moss
water sprite

1 paradise fish (female, I think)
3 julii cories
ghost shrimp

Future plans: java ferns, amazon swords, crypts, anubias, pennywort, one or two apple snails (same gender if possible).

I wanted to do a tank with a maximum amount of hardy fish. The cories and p-fish are air-breathers. This combined with the plants make dissolved oxygen in the tank less of a worry. Also, the cories stay in the bottom zone and the p-fish stays in the top zone mostly. The plants also help lessen the impact of the cycle (and I also used a bit of my friend's filter media- I would have used my own, but that tank is getting over an ich problem).

Good luck!

A betta would probably be okay with the current as long as it's not really violent water movement and there is somewhere in the tank that is still where it can rest.

It's tough to do a community in such a small tank because you're really limited on size and number of fish. I would personally get a few Platys for something that small (all male probably, if you dont want all sorts of fry) Maybe get a few Kuhli loaches for the bottom. I really wouldn't worry about the pH in this situation, unless you have really extreme water or want to keep delicate fish or do some breeding I haven't ever found it necessary.

Some something a little different you could try some Endler's livebearers, but females can be hard to find if you wanted to breed them.

Bettas can take a little current, so you could probably work that out somehow, and it would live nicely with Kuhlis. Get more than one Kuhli though, they tend to hide a lot no matter what (they need something in the tank to hide under/inside) but if you only have one, you may never see him lol. I had some, and I had these little ceramic huts, and the Kuhlis would go through the hole in the bottom and stick their heads out of the windows of the hut, they were cool.

You'll have to check, but I think the sailfin mollys get bigger than I'd go in a 5 gallon - which is to say, I think the sailfin types get bigger than black mollys, I know for sure the green sailfins get pretty big. Plus, most livebearers like a bit of salt in their water, but IME, mollys kind of need salt to thrive, and I dont think Kuhli loaches would go for too much salt.

Platys eat their fry, sometimes right after they're born, but they'll spawn so much you'll end up with fry if there's cover for them in the tank. It may not be too many in a 5 gallon though.

Sailfin mollies can get up to 6'' in length and they are really active, I would say no less than a 30g for them. How about a trio of guppies, 4 pygmy cories(or 2 kuhlies) and maybe a few otos?

Puma has good suggestions, except I would leave out the ottos unless you have a good amount of light on the tank and think algae could be a problem.

Mollies get way too big. The endler's suggestion was also a good one, if you can find them they are interesting little fish. Also if you can find a pair of killiefish they would do great in a tank that size. They are really nice looking too.

My 5 gal is finally cycled and stocked -
I've gone with two guppies, two Endlers, and two amano shrimp.

They all seem to be doing well so far...
The main problem I've had is finding plants that are small enough to fit in the tank and not look out of place - my tank is fairly short but long (about 2 feet across the front) - my local lfs doesn't have java moss or java fern.

Bear

I'm one of the other people working on a 5 gallon that Aquarius0015 mentioned. I think I've decided to go with White Cloud minnows. (I still go back on forth some.) They're a pretty little schooling fish that stays small. They work well for me because they can stay in an unheated tank, although some people do keep them in heated tanks.