Fish crepuscular

Bloater

Coregonus hoyi

The silver ghost of the Great Lakes, the Bloater is a master of the deep. This shimmering, iridescent whitefish thrives in the cold darkness where few other species dare to venture.

0 Sightings

0 Habitats

Quick Identification

straighten

Size

Typically 20–30 cm (8–12 inches) in length; weighing between 0.1–0.4 kg (0.2–0.9 lbs).

palette

Colors

Bright silvery body with an iridescent pink or purple luster on the sides; white underbelly and smoky-grey fins.

visibility

Key Features

Lower jaw is typically shorter than or equal to the upper jaw
Large, prominent eyes adapted for low-light depths
Slender, compressed body with a deeply forked tail
Small mouth positioned slightly downward

When You’ll See Them

schedule

Activity pattern crepuscular

brightness_5

Peak hours 9 PM - 3 AM (during vertical migration)

calendar_month

Season Year-round, with increased shallow-water sightings during winter spawning (January–March)

restaurant

Diet Primarily feeds on deep-water shrimp (Mysis diluviana) and amphipods (Diporeia), as well as various types of zooplankton.

park

Habitat Deep, cold freshwater lakes, specifically within the Great Lakes basin and Lake Nipigon, favoring underwater slopes and flat muddy bottoms.

bar_chart
Loading activity data...

Behavior

The Bloater is a deep-water specialist, primarily found in the cold, benthic regions of the Great Lakes. They are highly social fish that travel in large schools, often moving in response to the availability of tiny crustaceans and zooplankton. Their name comes from a unique physiological trait: when brought rapidly to the surface from deep water, their gas bladder expands, causing the fish to 'bloat'—an occurrence that early fishermen noted frequently.

Unlike many other whitefish species that prefer shallower reefs, Bloaters spend the majority of their lives at depths of 30 to 200 meters. They exhibit a behavior known as diel vertical migration, where they move higher in the water column during the night to feed on rising plankton and retreat to the darker, safer depths during the daylight hours to avoid predators like lake trout.

photo_camera EverydayEarth exclusive

Camera Tips

Capturing the Bloater on camera requires specialized underwater equipment, as these are not your typical 'backyard' visitors unless your backyard is a Great Lakes shoreline. To see them, you will need a submersible 'drop camera' or a tethered underwater trail camera capable of withstanding the high pressure of deep water. Because Bloaters are sensitive to light but also live in near-total darkness, using infrared (IR) LEDs is essential to capture footage without scaring the school away.

If you are deploying a camera from a pier or boat, aim for the 'thermocline' area—the transition layer between warmer surface water and the cold deep water—especially during the evening hours. Since Bloaters are attracted to food sources rather than salt licks or grains, a mesh bag filled with crushed fish eggs or ground-up shrimp can act as an effective lure. Secure the bait bag directly in the camera's field of view, roughly 2-3 feet away from the lens to ensure the AI can clearly identify the silvery scales and jaw structure.

During the winter months, Bloaters move into slightly shallower waters (60-100 feet) to spawn. This is the prime time for ice-fishing enthusiasts to deploy 'ice cams.' Set your camera to a high frame rate (60fps) if possible, as Bloaters are quick, darting swimmers. Position the camera at a downward 45-degree angle toward the lake floor to catch them as they forage along the bottom. Ensure your housing is rated for at least 100 feet of depth to prevent seal failure in the extreme cold of the Great Lakes.

Similar Species

Species that look similar or are commonly confused with Bloater.

Cisco

Larger than the bloater with a more prominent lower jaw and typically inhabits shallower water layers.

Lake Whitefish

Significantly larger with a much smaller, subterminal mouth and a distinct 'hump' behind the head in older individuals.

Kiyi

Even more specialized for deep water, the Kiyi has much larger eyes relative to its body size and longer pectoral fins.

Frequently Asked Questions

Bloaters are most active during the night and twilight hours. They participate in 'diel vertical migration,' swimming toward the surface under the cover of darkness to feed on plankton before returning to the depths at dawn.

To attract Bloaters, you must have access to deep Great Lakes water. Use an underwater camera with a 'chum' lure consisting of ground crustaceans or fish roe to draw them into the frame.

Their diet consists almost exclusively of deep-water invertebrates like Mysis shrimp, Diporeia amphipods, and various zooplankton found in the benthic zones of large lakes.

Only in coastal Great Lakes communities. While they aren't 'backyard' animals in the traditional sense, they are a vital part of the underwater ecosystem for residents living along the shores of Lakes Michigan, Huron, or Superior.

The easiest way to distinguish them is by size and jaw shape. Bloaters are generally smaller than Cisco, and their lower jaw is shorter than or equal to the upper jaw, whereas Ciscoes often have a slightly protruding lower jaw.

Record Bloater at your habitat

Connect a camera to start building your own species record — AI identifies every visitor automatically.

Join free Identify a photo