The water ran very fast in the brook. It ran over little stones.
The brook was fresh and clean. It was a good home for some water plants and some water animals.
Johnny Darter was a water animal and he lived in the brook.
He was a fish and he liked to swim in fast water.
He could swim up the brook and down the brook.
When he swam up he went head first. But when he swam down he went tail first.
Johnny Darter was a grown fish but he was a small one. He was not three inches long.
His eyes were near the top of his head. His mouth was wide. His head looked somewhat like the head of a frog. He had a row of dark marks on each side of his body.
This little fish had eight fins.
Two fins were along the middle of his back. He could put them up like little sails. Or he could put them down.
One fin was on the end of his tail.
One fin was on the middle of the under part of his body. It was not far from his tail.
Four fins were on his sides near his head. They were low on his body. There were two on each side.
He could move his four side fins like wings when he swam. He could put the ends down on the stones in the brook and walk with his fins.
One day Don and Nan caught Johnny Darter. They put him into a pail and looked at all his fins.
Then Nan said, "He is so scared! He wishes he were in the brook."
So they let Johnny Darter go back to his home in the brook.
"He swims up the brook faster than the water goes down!" said Don.