Fish for an uncovered nano tank?

[Hooz]

I'm looking for one more fish for a nano tank. I need more things eating and pooping in there. If they served some sort of utility as well, that'd be a bonus. The catch is, there is no cover, SO NO JUMPERS!

Cool inverts will also be considered, but I've already had a Blood Shrimp jump. :(

Current inhabitants are a single Springer's Damsel, a handful of tiny Blue Legged Hermits and an assortment of snails.

 

[doubleshot00]

Tailspot Blenny. Mines very chill

 

[Cthulukelele]

How big is the nano and how long have has the springeri been in there alone? Even though chrysiptera damsels are the nicer damsels, they can still bully most nano fish once established

 

[Hooz]

Tank has been running since December. The footprint is 16x12x7 for the display area.