Fish Active at night

Coastrange Sculpin

Cottus aleuticus

iNaturalist Wikipedia

A hidden gem of Pacific coastal waters, the Coastrange Sculpin is a master of camouflage that hops along the rocky bottoms of clear mountain streams.

0 Sightings

0 Habitats

Quick Identification

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Size

Typically 6 to 15 cm (2.4 to 6 inches) in length; weight is generally under 60 grams (2.1 oz).

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Colors

Dorsal side features mottled patterns of olive, dark brown, and grey for camouflage; the belly is white or light cream. Fins often have dark, wavy bars.

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Key Features

Broad, flattened head with a very wide mouth
Large, fan-shaped pectoral fins used for anchoring in currents
Smooth skin that lacks traditional scales
Two dorsal fins, the first having 8-10 flexible spines

When You’ll See Them

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Activity pattern Active at night

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Peak hours 10 PM - 3 AM

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Season Year-round

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Diet Benthic carnivore feeding on aquatic insect larvae (stoneflies, mayflies), small crustaceans, and occasionally the eggs or fry of salmonid species.

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Habitat Cool, clear coastal streams and rivers with rocky or gravelly bottoms; also found in some coastal lakes and brackish estuaries.

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Where Does the Coastrange Sculpin Live?

The Coastrange Sculpin is native to the Pacific coast of North America, spanning a massive latitudinal range from the Aleutian Islands and the Alaska Peninsula down through the coastal watersheds of British Columbia. Its reach continues through Washington and Oregon, terminating in the coastal streams of Southern California, specifically around Santa Barbara. While it is a freshwater species, it is rarely found more than 100 miles inland, as it prefers the temperate, maritime-influenced river systems of the immediate coast.

Basemap © OpenStreetMap contributors

2 Countries

1.2M km² Range

Least Concern Conservation

US United States

Marginal

CA Canada

Marginal

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iNaturalist / Verified observation data

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Behavior

The Coastrange Sculpin is a specialized bottom-dweller that has adapted perfectly to the high-energy environments of coastal streams. Lacking a swim bladder, these fish do not hover in the water column; instead, they 'hop' along the substrate in short, quick bursts. They are masters of stillness, using their mottled coloration to remain invisible to both predators and prey among the gravel and cobble of riverbeds.

These fish are primarily nocturnal, hiding deep within rocky crevices or under submerged woody debris during the daylight hours to avoid being spotted by herons or larger predatory fish. At night, they become active hunters, patrolling the bottom for small invertebrates. They are generally solitary and can be quite territorial, defending specific rock crevices that provide the best protection from the current and predators.

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Camera Tips

Capturing the Coastrange Sculpin requires an underwater approach. Since these fish are benthic (bottom-dwelling), you should place your camera in shallow riffles or the edges of pools where the water is no more than 6-12 inches deep. Use a waterproof action camera or a specialized underwater trail camera weighted down with a 'diving weight' or secured to a heavy flat rock using heavy-duty rubber bands. Angle the lens slightly downward to focus on the area immediately in front of a known hiding spot, like a large flat stone or a submerged log.

Because the Coastrange Sculpin is most active under the cover of darkness, lighting is critical. If your camera has a built-in infrared (IR) flash, ensure there are no floating bubbles or debris directly in front of the lens, as these will reflect light and cause 'white-out.' For the best results, place an external, waterproof IR light source a few inches to the side of the camera to provide side-lighting, which emphasizes the sculpin's unique texture and camouflaged patterns without blowing out the image.

To encourage a sculpin to stay in the camera's frame, you can gently disturb a few rocks upstream of your setup to release aquatic larvae into the current, or place a small mesh bag of crushed salmon roe (where legal) just 'upstream' of the camera's focal point. The scent will draw them out from their crevices. Set your camera to 'Video' or 'Burst' mode with a high frame rate, as their 'hopping' movements are very rapid and can appear blurry on standard photo settings.

Similar Species

Species that look similar or are commonly confused with Coastrange Sculpin.

Prickly Sculpin

Has a more 'rough' texture due to small scales (prickles) covering the body and a dark spot on the back of the first dorsal fin.

Torrent Sculpin

Features a more robust body and is typically found in faster-moving water; has two or three dark bands across the chin.

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Frequently Asked Questions

Coastrange Sculpins are primarily nocturnal. They are most active between dusk and dawn, emerging from under rocks at night to hunt for insects and small crustaceans when they are less visible to predators like herons.

You can attract them by placing your camera near rocky riffles or large submerged stones. Providing a scent trail using crushed aquatic insects or fish roe in a mesh bag can draw them out of hiding into the camera's field of view.

They are carnivorous bottom-feeders. Their diet consists mostly of aquatic insect larvae like stoneflies, caddisflies, and mayflies, as well as small snails, amphipods, and occasionally the eggs of spawning salmon.

Yes, they can be quite common in suburban areas of the Pacific Northwest and California, provided the local streams remain cool, clear, and have rocky substrates for hiding.

Coastrange Sculpins generally have smoother skin with few 'prickles' (scales) and the two dorsal fins are barely joined. Prickly Sculpins usually have more extensive prickling on their sides and a distinct dark spot at the rear of the first dorsal fin.

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