I see a lot of threads on the internet about people keeping snails to keep the tank clean, and an equal number who want to house shrimp with bettas. If you've read up on it at all, you'll see that it's a bit of a gamble when adding common ghost or cherry shrimp with a betta. Some do fine, some get eaten within minutes. All a matter of personality.
I wanted to make a recommendation for those looking to keep shrimp AND have a sparkling clean tank - Amano Shrimp. What sets them apart from other shrimp is their size. They get to be about two inches and are a good deal larger. Obviously, you can't keep them in a small bowl with a betta - but you really should know that tankmates are a bit out of the question in small living quarters.
Now, the best part... They're UNBELIEVABLE algae eaters. Not only are they fast moving, but are very thorough. I had an abalone shell in my tank that was died green from algae and looked like a green stone in appearance. Within 20 minutes or so, it was shimmering in the light and I couldn't find a trace of green on it. Additionally, I had a driftwood piece that had accumulated a pretty thick layer of dirt from the plants I added. I'm not certain if they moved it around or ate it, but the log is now dirt-free and looking great.
Keeping plants? These guys will eat all the algae off the leaves, stems and even the roots of plants like java ferns all without damaging even the most delicate of plants (Glossostigma, for example).
These guys aren't common in fish stores, but they're worth the extra effort to find. I've never had such an effective clean up crew and sparkling tank. Plus, they look really cool too. Sort of like a ghost shrimp with a fancy fan tail.
Only downside is they generally run about 5 dollars a piece in fish stores. I've read they have a much longer lifespan than typical shrimp though, so maybe that's not too bad of a deal.
Anyways, thought I'd share that information with those interested in keeping shrimp with their bettas, especially since nobody had made that suggestion on this forum.