This is the striped kuhli I was so worried about, always thinner than the others. Not any more! I really think it is from two things: once or twice a week feeding of sinking hikari wafers, and addition of leaf litter. Not sure if the kuhli is feeding off the biofilm on the leaves, feels more secure underneath them, or benefits from properties in the tannins, but nevertheless I'm very pleased!
I made sure to get more of these guava leaves in my next order from Tannin Aquatics- it's so cute to see the kuhlis underneath them, little leafy shelters.