Sharks nocturnal

Rusty Catshark

Halaelurus sellus

A pint-sized predator of the deep, the Rusty Catshark sports intricate saddle-like patterns that help it blend into the sunless seafloor. Found exclusively in the tropical waters off Australia, this elusive shark is a masterpiece of deep-sea evolution.

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Quick Identification

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Size

Males reach a maximum length of 35.3 cm (13.9 inches), while females are slightly larger, reaching up to 42.3 cm (16.7 inches).

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Colors

Tan to light brown base with dark reddish-brown 'rusty' saddle markings along the back and sides; some individuals show light spotting.

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Key Features

Slender, elongated body
Distinctive dark rusty-brown saddle markings
Broad, flattened head with a pointed snout
Two small dorsal fins set far back on the body

When You’ll See Them

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Activity pattern nocturnal

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Peak hours 10 PM - 3 AM

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Season Year-round

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Diet A benthic feeder that primarily consumes small crustaceans, such as shrimp and crabs, as well as mollusks and small bony fish.

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Habitat Deepwater tropical marine environments on the continental shelf and upper slopes, typically found on soft muddy or sandy bottoms.

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Behavior

The Rusty Catshark is a specialized bottom-dweller that spends much of its life navigating the sandy and muddy substrates of the deep ocean. Unlike the more famous predatory sharks of the open water, this species is relatively sedentary and slow-moving, using its slender body to glide just above the seafloor. It is primarily solitary, though it may be found in higher concentrations in areas where food sources like deep-sea crustaceans are abundant.

As a deepwater species, its behavior is dictated by the low-light, high-pressure environment of the continental shelf. It is not aggressive toward humans and, due to its depth range and small size, poses no threat. Most of its active life is spent scanning the sediment for movement, using highly sensitive electroreceptors to detect the tiny electrical pulses of hidden prey.

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Camera Tips

Capturing a Rusty Catshark on film requires specialized underwater equipment because they live at depths far beyond the reach of standard backyard gear. To see one, you would need to deploy a Baited Remote Underwater Video (BRUV) system. This involves housing a high-definition camera in a pressure-proof canister—typically made of aluminum or thick acrylic—and mounting it to a heavy steel frame that can withstand the currents of the eastern Indian Ocean. The camera should be angled slightly downward to capture the shark as it swims across the seafloor toward the bait.

Bait is the most critical factor for a successful 'capture.' Use a perforated mesh bag filled with oily baitfish like sardines or chopped squid. The scent plume is what will draw the Rusty Catshark from the darkness. Position the bait bag exactly 1 to 1.5 meters from the lens to ensure the shark stays within the camera's focal plane. Since the deep ocean is pitch black, you must provide your own light source; red-spectrum LEDs are preferred by researchers because many deep-sea creatures, including sharks, are less sensitive to red light, meaning they are less likely to be spooked by the artificial glare.

Because these sharks move slowly and purposefully, set your camera to record at 30 frames per second to save battery life and storage space. Use a high ISO setting to make the most of your LED illumination, but be careful of 'backscatter'—light reflecting off floating particles in the water—by positioning your lights off to the side of the lens rather than directly behind it. If you are using a triggered system, a time-lapse setting of one photo every 10 seconds can also be effective for monitoring the bait station over several hours.

Similar Species

Species that look similar or are commonly confused with Rusty Catshark.

Speckled Catshark

The Speckled Catshark features a more consistent pattern of tiny dark spots, whereas the Rusty Catshark has distinct, large saddle-like bands.

Australian Swellshark

The Swellshark is much bulkier and has the unique ability to swallow water to inflate its body, a defense mechanism the Rusty Catshark lacks.

Frequently Asked Questions

Rusty Catsharks are primarily nocturnal. They are most active during the late-night hours when they emerge to forage for small crustaceans along the seabed.

You cannot attract a Rusty Catshark to a typical backyard as they live hundreds of meters deep in the ocean. Marine scientists attract them using Baited Remote Underwater Video (BRUV) stations in deepwater habitats.

Their diet consists of small benthic organisms, including shrimp, crabs, small mollusks, and occasionally small fish found on the muddy ocean floor.

No, they are strictly marine animals found on the continental shelf of Western Australia. They never enter freshwater or shallow coastal suburban waters.

The Rusty Catshark is distinguished by its specific dark reddish-brown 'saddle' markings and its small size. The similar Speckled Catshark has a more uniform pattern of small spots rather than large bands.

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