Our Wild Neighbors

Dark Fishing Spider

Dolomedes tenebrosus

A riparian species of Eastern Canada rivers

Image of a Fishing Spider, seen from the front with its eight legs spread out.

Description of the animal

  • Semi-aquatic, large-bodied spider.
  • Body length: up to 28 millimetres for some species.
  • Abdomen varies from grey-brown to greenish-brown.
  • White spots and black W-shaped pattern on its back.
  • Light-coloured bands around its legs.

Habitat and needs

  • Usually lives on the banks of lakes, ponds, and streams. The Dark Fishing Spider is frequently found on stones, docks, and boats.
  • Spins a spherical silk cocoon after mating. The female lays up to 1000 eggs in it. She takes it with her everywhere, even into the water. Just before hatching, she attaches it to vegetation and spins a nursery web all around it.
  • Eats mostly insects. The Dark Fishing Spider captures them on the surface of or under water, in vegetation, or on the ground. It detects aquatic insects by clinging to the bank or dock with its back legs and letting its front legs skim the water surface. When it notices an appetizing insect, it grabs it with its legs and fangs. It dives underwater if needed.
  • Can stay underwater for several minutes, especially if it remains immobile. It breathes the air trapped under the hair on its body.
  • On the ground, it soemtimes travel great distances and strays quite far from waterways.


  • The Dark Fishing Spider clings to boats and wharves.
  • It is reassuring to those with a spider phobia to know that the Dark Fishing Spider does not attack humans. Most of the time, it flees when it feels threatened. It can, however, be aggressive when defending its cocoon.
  • The Dark Fishing Spider acts as food for several types of edible fish.
  • It eats insect pests, like mosquitoes.

Living with them

  • Live and let live is its motto!
  • Avoid disturbing it or picking it up, because it could bite and its venom is quite painful. If it has the option, the Dark Fishing Spider prefers to flee!

Participating cities where this animal has been seen