I caught 3 little minnows in a creek by just scooping up a bucket full of water, and catching one in a small net. I didn't realize I had 4 fish until we got them home and moved them into the aquarium. They turned out to be mosquitofish, they very common in this area. They were very small, but they grew quickly. And drastically reduced the variety of live in our aquarium. Turned out we had 3 males and 1 female, so we took 2 males back to the creek and kept only one female and a male. This still seems to be too great a burden on the eco system. We catch mosquito larvae from other water sources around and dump them into the aquarium. The mosquitofish clean them up in very short time. The female looks to be quite pregnant already, so we are going to wait until she delivers and then release the adults and most of the babies. We will eventually thin it down to ONE male mosquito fish only, and see if the ecosystem can handle that.
Its HARD to get pictures of the fish, they don't ever stay still!
The egg case on the rock in the background is PROBABLY snail eggs, but its much smaller than the other egg cases we thought were snail eggs, so it might be something else.