Fish
Longnose Dace
Rhinichthys cataractae · also called longnose dace
In the fastest, most turbulent stretch of a rocky stream riffle, where the current would sweep most small fish away in an instant, a longnose dace holds its position effortlessly, its flattened head and overhanging snout shaped by evolution for exactly this kind of water.
Overview
The longnose dace, Rhinichthys cataractae, is a small, current-loving fish native to fast, rocky riffle habitat in streams and rivers across a vast range spanning most of the United States and Canada. Its distinctively flattened, drag-reducing head shape, unusual comfort in the fastest available water, and status as one of the most widely distributed small fish on the continent make it a quietly successful specialist of turbulent streams.
A fish that chose the hardest water on purpose
Rather than competing with other small fish in gentler currents, the longnose dace has specialised in exactly the fast, turbulent water most fish avoid, trading difficulty for a food supply that comes with far less competition.
Status
Least Concern — widespread and abundant across suitable fast-flowing stream and river habitat throughout its very broad range across North America.
Longnose Dace: common questions
Why does the longnose dace have such a distinctive shaped head?
This species has a flattened head, a small underslung mouth, and a snout that overhangs it, a body shape that reduces drag and helps the fish stay pressed firmly against the streambed even in the fastest, most turbulent riffle water, letting it feed and hold its position where many other small fish simply cannot maintain themselves.
Why does the longnose dace live in such fast water?
By specialising in the strongest currents within a stream, this species avoids direct competition with many other small fish that cannot hold their position in equally fast water, giving it access to food resources, mainly aquatic insect larvae clinging to rocks, that are less contested than in slower, calmer stretches of the same stream.
How widespread is the longnose dace?
This species has one of the broadest ranges of any small North American fish, found from the Atlantic coast to the Pacific coast and well up into Canada, a distribution made possible by its tolerance for the fast, rocky, well-oxygenated riffle habitat found in suitable streams across a huge portion of the continent.
How long does a longnose dace live?
This species is relatively short-lived for a fish, typically surviving only a few years in the wild, and it reaches a modest adult size of around 10 to 12 centimetres, considerably smaller than many of the larger fish species sharing the same streams.