Fourspine Stickleback
The fourspine stickleback is a thumbnail-sized fish — rarely more than 5 cm — native to Atlantic Canada from Newfoundland and Labrador through the Maritime provinces and Quebec.
It's not a sport fish in any conventional sense, but it matters to anglers as forage for larger predators and as a fascinating subject for naturalists, dip-netters, and anyone curious about what lives in the weedy shallows of a tidal creek or coastal marsh.
Also known as Bloody stickleback, four-spined stickleback
- Tiny, elongated body — common length around 4 cm, maximum around 6.4 cm — with a distinctly slim, keeled tail base that lets it snap-turn through dense vegetation.
- Two to four free dorsal spines that angle alternately left and right, plus a spine attached to the dorsal fin; these lock upright and can draw blood if you palm the fish carelessly.
- Brown to olive-green on the back and sides with dark mottling; silvery-white belly. No scales — the skin is bare.
- Breeding males develop vivid red pelvic fins — the clearest field mark separating them from the similar ninespine stickleback sharing the same coastal marshes.
What to know
Habitat Distribution
- Native to Atlantic Canada: Newfoundland, Labrador, the Maritime provinces, and Quebec — the most easterly-confined of Canada's five stickleback species.
- Primarily a nearshore marine and estuarine fish, living in shallow bays, salt marshes, and tidal creeks, but tolerates a wider salinity range than any other North American stickleback.
- Some landlocked freshwater populations exist in Nova Scotia lakes, and the species moves into coastal streams above the salt wedge where aquatic vegetation is dense.
- Depth range is very shallow — typically 0 to 3 m — in weedy, low-energy water.
Key Locations
- Coastal salt marshes and tidal creeks throughout Nova Scotia and New Brunswick — the core of its Canadian range and where landlocked lake populations also exist in Nova Scotia.
- Newfoundland and Labrador coastal waters — confirmed native, found in nearshore marine and brackish habitats along the island and coast.
- Gulf of St. Lawrence shoreline in Quebec — the northern edge of its documented Canadian range.
Specific Spots
- Dense aquatic vegetation in tidal creeks and salt-marsh channels: this is where males build nests and where the fish spend most of their lives, using the weeds for cover from predators.
- Backwater areas and sheltered coves with little current — the slim caudal keel helps them maneuver in weeds, but they avoid strong tidal flow.
- The transition zone just above the salt wedge in coastal streams, where brackish water meets fresh — salinity tolerance makes this edge habitat productive for the species.
Fourspine Stickleback FAQ
Answers from onWater's species guide.
How do you catch Fourspine Stickleback?
The fourspine stickleback is not a target species for rod-and-reel anglers. It's most commonly encountered by naturalists and researchers using small-mesh dip nets or seines in tidal creeks and salt-marsh channels.
What do Fourspine Stickleback eat?
Feeds along the bottom on small crustaceans, worms, diatoms, insect larvae, and fish eggs, essentially whatever invertebrate prey is available at that scale. This makes them important forage for larger predators like striped bass and sea trout working the same tidal shallows.
Where do Fourspine Stickleback live?
Native to Atlantic Canada: Newfoundland, Labrador, the Maritime provinces, and Quebec, the most easterly-confined of Canada's five stickleback species.
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