10 gallon divided

I have recently bought a 10 gallon all glass aquarium with a powerhead spongefilter and 6 kg gravel stones. I am thinking of keeping just a betta inside this tank and need some ideas for plants which are low maintainence and do not require a lot of fertilizers. I am currently cycling this tank...

One of my sorority girls, Lapis, is not in the best shape. :/ She's the smallest and I believe youngest out of the bunch (She's probably a juvi), and on top of all that the most recent. She's a inch long, with mustard gas coloration.   She isn't lethargic, she eats well, and isn't fin rotting...