Of course, being able to evade humans is a necessity. “However, many fishes do indeed stop growing at some point.” “Many fishes start reproducing and then continue growing and reproducing for years and years to come,” he says. In fact, there may not be a limit on how big a fish can grow, Oldfield says, as the more than 35,000 diverse species on Earth often exhibit indeterminate growth, allowing them to continue growing throughout their entire lives. “The trouble is that these large rivers tend to get dammed, which messes up reproduction, so the really big species go extinct or become rare,” he says. He says the adequate space allows a fish to grow big and not get stranded while having the opportunity to get enough food.Īnd Janssen doesn’t think the recent catch is an outlier, either for its species or for other large, old-river species. John Janssen, Ph.D., a professor at the University of Wisconsin-Milwaukee’s School of Freshwater Sciences, tells Popular Mechanics the Mekong is an old, large river, which allows enough time for evolution to produce an extra-large fish. Huge catfish hauled from Mekong River being admired by locals. New dams could fragment habitats, lead to overfishing, and threaten the giant Mekong species, Hogan says. The Mekong River, already with a storied history of mega-sized freshwater fish, runs through six countries-China, Myanmar, Laos, Thailand, Cambodia, and Vietnam-but new dams can dampen fish’s ability to naturally grow. Ronald Oldfield, Ph.D, a senior instructor at Case Western Reserve University, tells Popular Mechanics that capturing such a large fish in the Mekong River shows it “might not be too late and the river might still be capable of supporting such large fishes if it is managed wisely.” “It’s an issue throughout Asia, where populations of giant freshwater fish have declined by over 95 percent since 1970.” “Unfortunately, populations of most of these species have plummeted, and some are now on the brink of extinction,” Hogan says. A handful of giant stingrays have already been seen in the area this year, leading researchers to believe the spot could be a popular spawning location. In fact, the Mekong River is home to many of the world’s largest freshwater fish: giant freshwater stingray, giant barb, giant pangasius, seven-striped bard, giant wallago catfish, and goonch catfish.” The area is also home to freshwater dolphins and giant soft-shell turtles. So, historically, the Mekong has been a great place to be a big fish. “Over two million tons of fish are harvested from the Mekong River each year. “The Mekong is one of the largest and most productive rivers in the world,” Hogan explains. Everything Needed to Get Started in Magnet Fishingīut getting so large was more a product of space and food access than anything else.

Zeb Hogan, Ph.D., a research biologist at the University of Nevada, Reno and director of the Wonders of Mekong project, tells Popular Mechanics that finding a fish of this size offers “an indication that this stretch of the Mekong River, the longest remaining free-flowing section, is still relatively healthy.” Let’s nerd out over them together-join Pop Mech Pro. But how did these fish become so huge in the first place? 🐟 You love weird animals. The stingray-which researchers with the Wonders of the Mekong conservation project saved-beat out the previous freshwater record-holder, a 646-pound catfish found in Thailand in 2005, also in the Mekong River. Earlier this month, a local fisherman caught the beast in the Mekong River, located in northeastern Cambodia. Now, familiarize yourself with the new record-holder in the largest freshwater fish category: a giant stingray that measures about 13 feet long and weighs 660 pounds. If you’re a fan of giant fish, you already know about the Mekong River. To grow huge, it’s essential to have enough space and access to food.

Researchers say the massive growth of this fish showcases the relative health of a stretch of the Mekong River.

A local fisherman in northeastern Cambodia caught a 660-pound stingray in the Mekong River and alerted scientists with the Wonders of the Mekong project.

Biggest freshwater fish in the world