Stonecat

Fascinating facts about the Stonecat

• A wasp-like sting comes from the stonecat’s pectoral spine, which hides venom glands at its base and can cause pain as intense as a wasp’s sting, reminding anglers that these tiny catfishes are armed defenders.
• Stonecats can stretch up to a foot long and weigh as much as 1.1 lb, yet most individuals stay between four and eight inches, showing how much size variation can exist in a single freshwater species.
• When water warms to 25 °C, stonecat couples lock in monogamous pairs and the male guards the clutch under flat rocks averaging 200 sq in in area, a tiny fortress protecting up to 1,200 amber-yellow eggs each season.
• These catfishes hug riffles from shallow streams to depths of three meters, preferring fast-moving, rocky substrates, which is why their presence signals clean, well-oxygenated water in rivers from the Great Lakes to the Red River basin.
• A stonecat’s anal fin has 15–18 rays, the pectoral fin 9–11, and the caudal fin up to 67 rays, a skeletal checklist that helps biologists differentiate it from look-alikes and track its widespread range across North America.

At a glance

About the Stonecat

The stonecat (Noturus flavus) is a sleek, flat-headed catfish that slips beneath the stones of fast-moving riffles, its yellowish-brown skin blending with the gravel while a whitish belly flashes in the current. Its slender body, typically four to eight inches long but capable of reaching twelve, is topped by a continuous adipose-caudal fin keel and a dorsal spine that, unlike many of its relatives, bears venom glands at the base of the pectoral spines, delivering a sting as sharp as a wasp’s. Two distinct forms roam its range: one in Tennessee’s Cumberland drainage bears twin light bars on the nape, while elsewhere a single patch replaces the bars, both marked by white spots at the dorsal fin base and on the upper caudal edge. Stonecats inhabit a vast swath of North America, from the Great Lakes and St. Lawrence River to the Mississippi basin, extending west to Alberta and south to northern Alabama. They favor moderate-to-fast riffles with rocky substrates, often nesting under large, flat rocks in pools where males guard amber-yellow eggs up to four millimeters across. By night they use sensitive barbels to scour the bottom for mayfly larvae, crayfish, minnows, and even plant matter, a truly opportunistic diet that underscores their role as both predator and indicator of pristine, well-oxygenated waters.

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