Jeff Bonawitz of Lancaster County struggled for nearly a half-hour before landing a flathead catfish the size of a 7-year-old child.

His achievement aside, the species is considered invasive, and its growing numbers are of concern.

Bonawitz, 54, of East Lampeter, launched his boat with a friend April 6 from Muddy Creek, a tributary of the Susquehanna River, in York County. He used a bluegill as bait on an 8-foot rod using 25-pound monofilament line.

“When I finally pulled, it just bent the rod straight down," Bonawitz told the state Fish and Boat Commission, which verified the catch. "I could tell it was big. It kept hanging down deep, and when it finally came up to the top, we thought it might be a mermaid. I’ve fished the Susquehanna for years and I’ve never caught anything quite like it.”

It took Bonawitz 25 minutes to land the 50-pound, 7-ounce fish. It measured 45.25 inches long. Its girth was 31.25 inches.

The previous state record was 48 pounds, 5 ounces for a flathead catfish caught in Berks County. Pennsylvania state record fish are judged by weight.

Bonawitz called the Fish and Boat Commission to verify the weight. Waterways Conservation Officer Jeffrey Schmidt confirmed that it was a record and reviewed photos taken immediately after the catch.

The fish was released back into the Susquehanna beneath the Wrightsville Bridge.

"It was such an amazing fish," said Bonawitz. "I thought the best thing to do was put it back so that maybe the next guy could catch it. I have a feeling this record may not last very long."

Flatheads are invasive, according to the federal government, and a threat to not only the Susquehanna, but the Chesapeake River into which it drains. Catfish become top predators, preying on native fish and other aquatic life.

Pylodictis olivaris, also known as the mudfish or shovelfish, is native to drainages around the Mississippi River and Gulf of Mexico, but has spread way beyond its normal range. It is a big carnivore that has been found as large as 130 pounds — making it popular with anglers because of its size and taste.

Starting as far back as the 1950s and 60s, they were stocked or released into other areas. The first release into the Chesapeake in 1965 was accidental. Populations spread into the Susquehanna and Schuylkill.

Officials from the Chesapeake Bay Program, charged with leading the restoration of the bay, are concerned about the growing numbers of flatheads and their potential impact on menhaden and blue crabs.

But since the flatheads are already in the waterways and there’s little that can be done to get rid of them, anglers have taken advantage of the opportunity to catch really big fish.