I'm looking into Kuhli loaches and I keep seeing conflicting information regarding their ability to live with bettas... Does anyone have experience with keeping these two in a tank together? For reference, I'm thinking of getting a female betta so I'm hoping she won't be particularly aggressive.
Depends on the personality of the betta, like SaraB stated. Some bettas can get along with companions (I've heard people doing kuhlis) and some bettas can't. My bettas get along well with a variety of other fish in a 72G. I think it also depends on the size of your tank, obviously a smaller space can be more challenging with potentially aggressive and territorial fish like bettas. You could always try it out and keep a watchful eye on everybody. Make sure you have a backup plan in case it doesn't work out- because it truly could go either way.
I would think 30G would be a good size to keep everybody happy. I would definitely ensure there is lots of coverage and hiding spots. I would not use too bright of a light- your betta will stay towards the top of the tank if it's not too bright. That will allow the loaches to hang out at the bottom without the betta down there to bother them.