i used to have some in with my betta, they were very fun and i trained mine to eat pellets and flakes. they look cool when they eat.
i just changed the water like a normal tank and they were fine. i even put them in with my baby red eared sliders in their 10 gal, they lived in there till i moved them back into my betta tank. i dont even remember that happened to them, i guess they died?