The mouth of the canal was clogged with boats – we counted 13, and a few more were anchored further up in the canal.
Word had spread: the tilapia were running. The parking lot at Flippers Marina where we launched was jammed, as more and more fishermen rolled in.
Not too long ago most area fishermen probably had never seen a tilapia – a fish native to Asia and classified as invasive species in Tennessee – much less caught one.
That changed in 2010 when flooding along the Cumberland River washed tilapia from some stocked ponds into Old Hickory Lake.
Tilapia are extremely prolific, with monthly spawns of as many as 1,000 fry, and their population quickly exploded. Tilapia are now in the lake by the thousands, ranging in size from one inch to over nine pounds.
Among the anglers drawn to the Old Hickory tilapia explosion is Frank Fiss, the Tennessee Wildlife Resources Agency’s Chief of Fisheries. When I talked with Frank last week, he had made two tilapia trips and was planning another.
“There’s no question that it’s a popular fishery,” Frank said about Old Hickory’s overnight tilapia craze. “People enjoy catching them.”
The first time I heard about tilapia in Old Hickory was about four years ago when Hendersonville fishermen Paul Neighbors emailed some photos of catches he was making.
Biologists initially believed the tilapia would die out since they theoretically can’t survive water temperatures below 58 degrees for a prolonged period. But recent winters have not only been milder than normal, the canal water below the Gallatin Steam Plant is considerably warmer.
That’s where the fish congregate when temperatures start to cool, stacked in by the thousands. Sherborne and I caught around 100 during our recent trip, with the biggest about two pounds. Since tilapia are a non-game species, is no size limit or creel limit.
Tilapia have a mixed reputation. They received some negative exposure on an episode of the “Dirty Jobs” TV show when host Mike Rowe Rhodes showed how they are used to clean commercial fish tanks by eating the other fishes’ feces.
But tilapia are a valued food fish world-wide, including restaurants and markets in the U.S. When raised in clean water they are as edible as any other fish species.
Since they are fun to catch and good to eat, what’s the drawback?
“We don’t know if there is one,” Fiss says. “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. Since they don’t feed on minnows, they don’t compete with crappie and bass. In fact, Fiss says, small tilapia could be a prime forage fish for bass.
Fiss says as far as he knows, Old Hickory Lake is the only water in the state in which tilapia are present, other than in stocked private ponds.
What the future holds – if the tilapia will eventually die out after a hard freeze, or if their population will continue to explode, with adverse effects – is unknown. Right now all anyone knows for sure is that they are teeming in Old Hickory Lake, to the delight of flocks of fishermen.