Beautiful set-up. Are you planning on filling it right up to the top? That would increase your total water volume considerably; or are you keeping exposed rocks at one end for a specific reason?
Are you allowed in your state to set minnow traps for bait minnows? I have had outstanding success in catching small fish using these inexpensive traps; I release probably 99% of the fish I catch, but have come up with some very interesting specimens this way. Sticklebacks would be perfect for that tank. Emerald Shiners as well are fond of current; they're delicate to transport, but any that survive the first week tend to live long lives and they are very active and add a lot of life to a tank.
I don't know if you have those species, but there are probably many other types available to you locally.