There are a lot of fish species that call the Alexandria Chain of Lakes home, but one that anglers never really expect to latch into is a rainbow trout.

That’s exactly what Alexandria’s Tim Olson did while fishing on Lake Carlos on the evening of July 1. Olson was pulling crankbaits in about 110 feet of water hoping to run into walleyes suspended in the water column. Instead, he landed a big rainbow that measured 24.25-inches.

“This thing hit on a bait that was probably about 30 feet down,” Olson said. “It didn’t necessarily fight that hard. By the time I got the rod out of the rod holder, the fish was actually flipping around up on the surface. It had come up that quick, which kind of surprised me. I was thinking it was probably a little northern at first, so we were surprised when we got it to the boat.”

Olson knew catching a rainbow like this on the chain was a rarity. The picture quickly got to Bill McKibbin, the assistant area supervisor for the Glenwood DNR fisheries department.

“Bill’s response was, ‘No way,’” Olson said.

Glenwood DNR fisheries supervisor Dean Beck could not say with certainty how the fish got in the lake, but he did have a theory.

“We issued a private fish hatchery license to an individual who raised fish in ponds just northwest of Lake Carlos,” Beck said. “His license included rainbow and brown trout. This individual is no longer licensed, but it is possible some trout may have escaped to Lake Carlos. Such catches would be extremely rare in absence of local production.”

One other possibility stems from stocking efforts miles away, but the timing of that and the length of this fish do not seem to match up.

The Viking Sportsmen group in Alexandria initiated a stocking effort of rainbow and brown trout in Douglas County into Spruce Creek, a spring-fed tributary of the Long Prairie River, starting in the spring of 2019. The Long Prairie River runs into the northeast portion of Lake Carlos.

Olson, a board member for the Viking Sportsmen, has been active in the stocking efforts of trout into Spruce Creek in the last year and a half.

“There’s nothing that we’ve put into Spruce Creek either last spring or this spring that is big enough for this,” Olson said. “Bill McKibbin called me this morning. We were talking about it too, and I think in the early 2000s, someone in a gill net had caught one out of Carlos, and they had no clue where that came from, other than maybe it got in there from a previous Spruce Creek stocking from however many years ago.”

The DNR did run a trout-stocking program north of the Spruce Center Dam on a stretch of stream that runs into Otter Tail County. That started in the 1970s and lasted almost a decade.

“This spring in the stocking that we did, we had about three rainbows that were probably 20 inches,” Olson said. “This one was four inches longer than those, so this obviously wasn’t that. Then the ones we stocked in the spring of 2019, there maybe was a few 17-18 inchers in there, but most of those fish were in that seven, eight, nine-inch range.”

Beck said he wouldn’t completely rule out that the fish caught by Olson was one of those larger rainbows released in Spruce Creek in 2019.

“That would be fast growth, particularly since it was a sexually mature fish,” he said. “It’s hard to get around that rate of growth to be comfortable that it was one of the few larger fish stocked last year.”

Beck said rainbow trout can live to be 20-plus years old. At more than 24 inches, Olson caught a good-sized rainbow, but aging it by its length isn’t easy.

“I’m hesitant to guess at the age of the fish without knowledge of whether the trout were fed on a daily basis or allowed to fend for themselves in ponds,” Beck said. “If fed daily, that fish may be 5–7 years old. If food is scarce, the fish might be much older.”

Beck also said that they do maintain a trout display pond on the Glenwood Area Fisheries campus. Olson’s catch on Carlos is certainly rare for lakes in the Alexandria area, but not entirely unheard of.

“There is some natural reproduction in the stream above our display pond,” Beck said. “Escapes do occur when we lower the pond for cleaning. Trout catches are also rare in Lake Minnewaska, but they do occur.”

Lake Carlos is one of the deepest lakes in the Alexandria area, with a maximum depth of 163 feet. That means some cooler water temperatures that trout like are available.

The fish Olson caught is still swimming out there after he took a measurement and a few photos before releasing it back into the lake.

“It took right off,” Olson said. “I was expecting a northern, or even a tullibee or something. To be kind of an oddball species for our area of the state. We do have the Spruce Creek stocking going on now, but I definitely never would have guessed what it ended up being.”