Getting rid of Guppies?! Gulp! Sorry... I love my Guppies! Anyhoo, Rummynose (tetra or rasbora) come from a soft and acid environment, but can be acclimated somewhat. When I worked at a wholsealer we started them off with soft and acid and got them acclimated to ~7.4pH, which was what the tap water was. They are a touchy fish. Not the best choice for Bettas, but if you can get conditions gradually, with hiding places, it's possible. I'd keep the Guppies and add a few more plants!

Glad you posted this thread. I bought 3 rummy nose tetras and had them in the bag floating in the tank. It's been about an hour and I totally forgot them till I read this. I think there pretty adaptable and should do ok if water parameters are good.

Well, I might give it a try... I'm always looking for a challenge, which is why I'd like to get rid of the guppies... by which I mean, donate them to a friends tank who has quite a bit of experience! lol
Last time I added some live plants I had a guppy explosion! At the time, I had turtles and used them as food (they weren't fancytails, they were a feeder guppy but after several generations of breeding they were actually quite pretty. Anyway, no more turtles, so that won't be an issue! A 10 gallon limits me... I could pull out my 25gallon tall or my 30 gallon, but my husband won't let me get the 55, 50, or 80 going. I can't blame him... we've got a baby on the way and they take some maintenance. Well, thanks for everyones thoughts........

I can't answer the question about rummynose tetras....

But if you are looking for tetras to keep with a betta - my pH settles to about 7.5 (comes out of the tap at 8+) and I've successfully kept lemon tetras and glolite tetras with bettas for years.

What is the water hardness? Here, our hardness is very low (New England water is naturally soft and acidic) but the water company adds sodium carbonate to raise the pH, which is why it's 7.5. I think the hardness may be more important than just pH.

fgilles - thanks for the info... I actually have two lemon tetras in there right now with my guppies and although I was pretty sure it was my guppies that were nipping the last betta we kept, I couldn't rule out the lemon tetras. I have also kept glowlight tetras in the past and may look at that again as an option. Thanks!