PENN TWP — Fifty Butler Intermediate High School students spent the past six months hatching and caring for 236 brook trout.

On Wednesday they set them free in Thorn Creek.

“You've done a good job taking care of the fish during the year. These are some of the nicest fish we've ever had,” science teacher David Andrews told the group.

This was the eighth year that the school has had its Trout in the Classroom program capped by a trout release day where the students spend the day in nature learning about fly fishing, looking at specimens and planting trees.

The event was sponsored by XTO Energy and the Butler Golden Tornado Scholastic Foundation and included participation from the state Fish and Boat Commission, the Butler County Conservation District, PA Council Trout Unlimited and the Department of Environmental Protection.

For the first three years of the program, students released their trout into the Connoquenessing Creek. For the past five years they have held the release day on property owned by John Pyzdrowski.

With help from Ryan Harr of the county conservation district, the students looked at macrovinvertibrates from the stream, such as mayflies and stoneflies.

The insects can be used to monitor the health of the stream, Harr said.

“If you take a water sample, that's a snapshot, that's one moment in time. With macroinvertebrates, they have a life cycle. If something happened in the steam a month ago or six months ago, that would have an impact on these critters,” he said.

Fish and Boat Commission biologists Tim Wilson and Freeman Johns demonstrated electrofishing, a method of estimating how many fish are in a stream by briefly stunning them with electricity.

The segment of the creek that goes through Pyzdrowski's property has been part of a habitat improvement program done by the Connoquenessing Watershed Alliance and sponsored by XTO Energy since 2012.

As a result of logging and other human development, the stream banks have eroded in many places. But by rehabilitating the stream banks, groups are able to improve the quality of the habitat and allow for more fish and other species to live there, Wilson said.

They have made the streams narrower, but deeper. Groups also have lowered the water temperature by planting trees near the creek, which create a riparian buffer area.

By improving the stream conditions, the state has been able to stock more trout there, which means more fish for fishermen.

“We've seen a good jump in the number of fishermen who fish here,” Wilson said about Thorn Creek.

This year, the commission will stock 3.2 million trout around the state, most of which are hatched at its eight hatcheries, he said.

The trout class is one of 12 classes offered to about 220 seventh and eighth grade students who are in the school's enrichment studies program, Andrews said.

“Being outside and relating the in-class lessons to what is in the environment is good for them and they like to spend the day in nature,” Andrews said about the trout release day.

There is a waiting list for the class, which is quite popular.

“This is unlike anything they do at any other school. It's a once-in-a-lifetime opportunity,” eight grader Harper Jack said.

The students got the fish eggs in November and cared for them daily after they hatched. This included feeding them and testing the water for pH, ammonia and nitrate levels.

Most of the fish were 4 to 8 inches long when they were released.

Seventh grader Sarah Fiorina said the class was an opportunity to help improve the environment.

“I love the outdoors personally, and I love being involved in the community,” she said.