The darters are a colourful group of little fish, and one of the most spectacular is the male Iowa Darter, somewhat visible next to the brown female in this photo. To see what they really look like check out this link. We got good looks through binoculars but neither my camera nor my photography skills were up for the task!
Sticklebacks are tiny fish with intensely complex spawning behaviour, where males build a nest and then display to a female to get her to use it. Males like this one may turn black during spawning, but are inconspicuous and brown the rest of the year. I'm not sure whether this is a Brook or a Ninespine Stickleback.
Brook Trout are often better known as Speckled Trout based on the distinctive back pattern. Although they are popularly fished, I rarely see this species so was pleased to get good views of several small individuals in this clear pool.