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By Larry Woody, Outdoors Writer

Tilapia, a fish native to warm climates, aren’t supposed to be able to survive cold Tennessee winters.

Somebody forgot to tell the tilapia.

Or at least they forgot to tell the ones that arrived in Old Hickory Lake around 2010 when flooding along the Cumberland River washed in some of the fish from upriver stocked ponds.

In recent years more and more fishermen have discovered the hard-fighting, good-eating fish, and alhough they are classified as an invasive species by the Tennessee Wildlife Resources Agency, they have gained a devoted following.

Submitted photo
Bob Sherborne caught this big tilapia in Old Hickory Lake.

Even the TWRA’s Chief of Fisheries, Frank Fiss, admits he enjoys catching them.

About this time last year fishing buddy Bob Sherborne and I went on a tilapia trip below the Gallatin Steam Plant, where the fish congregate in the warmer discharge water. We found ourselves in a nautical traffic jam. We counted 13 boats anchored in one spot, with more further up the canal. Everybody was catching tilapia.

Sherborne and I caught around 100 and kept 30 of the biggest, the largest of which weighed around two pounds. (There is no size or creel limit.) I baked mine and they were delicious.

We haven’t yet made it back this year, but a friend fished there recently and brought home 36.

Tilapia are extremely prolific, with monthly spawns of as many as 1,000 fry, which explains why their population quickly exploded in Old Hickory Lake. They are there by the countless thousands, ranging in size from one inch to over nine pounds.

They are easy to catch: put a pinch of worm below a bobber and fish it just as you fish for bluegill. We caught ours 4-6 feet deep.

The first time I heard about tilapia in Old Hickory was four years ago when Hendersonville fishermen Paul Neighbors emailed some photos of his catches.

Biologists initially believed the fish would die out since they theoretically can’t survive water temperatures below 58 degrees for a prolonged period. But the discharged water below the Gallatin Steam Plant tends to be warmer. It is possible the fish are adapting to cooler water elsewhere in the lake.

Tilapia have a mixed reputation. They received some negative exposure on an episode of the “Dirty Jobs” TV show when host Mike Rowe explained how they are used to clean commercial fish tanks and ponds by eating other fishes’ feces.

But tilapia are a valued food fish worldwide, including restaurants and markets in the U.S. When raised in clean water they are as edible as any other species.

Since they are fun to catch and good to eat, what’s the drawback?

“We don’t know if there is one,” Fiss admits. “Generally we are concerned over the presence of any invasive species, but we haven’t done any studies on tilapia. It’s something we will keep an eye on if they continue to thrive in Old Hickory.”

Tilapia feed primarily on algae and other vegetation but will also eat worms and insects. That puts them in competition with native species such as bluegill, but so far there has been no adverse impact – bluegill remain as plentiful in Old Hickory Lake as ever. Since they don’t feed on minnows, tilapia don’t compete with crappie and bass. In fact, Fiss says, small tilapia could be a prime forage fish for bass.

Whatever their impact – positive or negative – it appears tilapia have become permanent residents in Old Hickory Lake. We might as well enjoy them.