Please use the PM function in the future if you only want Jan to answer your question. 
I don't mean to bud in, but I'd like to help out. When you're looking to add new fish you have to ask yourself "Does my tank already look full or does it need something extra?" Your tank looks like it has all the levels full(bottom, middle, and top), but your Pencilfish school may need expanding(add 5 more). Personally, I don't see room for adding a new school, but that's just me.
I don't mean to bud in, but I'd like to help out. When you're looking to add new fish you have to ask yourself "Does my tank already look full or does it need something extra?" Your tank looks like it has all the levels full(bottom, middle, and top), but your Pencilfish school may need expanding(add 5 more). Personally, I don't see room for adding a new school, but that's just me.