I use a different species than most people. I use rosey reds. The are a pink colored version of fat head minnows. They are egg layers and and grow to about 2 1/2 inches. They only live about 2 1/2 years, but are very prolific. Have them in all of my earthbottom ponds and outdoor lined ponds. They number in the thousands in the earth bottom ponds. Very hardy. I like to joke about them by saying they only know how to eat, breed, and be eaten. They can be found at many pet stores as feeder fish and are very inexpensive. If you sort out any black or grey ones you will only get pink offspring which I like because they are easy to see and monitor. Started with about 1 &1/2 dozen many years ago in a large empty pond early one summer. By the middle of the next summer in that 90 ft. wide pond the water was covered with them. They dwindled a lot when that pond was stocked with other fish, but never have died out. I placed a few in the lined ponds and usually have a dozen or so left to restart in spring. When they gets lots of sun in the summer they turn a pale orange. Never seen mosquitoe larvae or any other small bugs in the water if they are there. Quite popular up here in the North in ornamental ponds.
Mikel