A spider that can run across a pond—and sometimes catch a fish—sounds improbable. Yet that is exactly what some fishing spiders do. These long-legged hunters can detect tiny movements in the water, sprint across its surface, and retreat beneath it when threatened. Despite their intimidating size, they are generally shy around people.
Fishing spiders are most often discussed as members of the genus Dolomedes. They occur in many parts of the world, although their colors, sizes, habitats, and behavior vary by species. This guide explains how to recognize them, what they eat, where to find them, and what to know about bites.
| Common name | Fishing spider; some species are also called raft or dock spiders |
|---|---|
| Scientific group | Genus Dolomedes; family Dolomedidae |
| Typical appearance | Large, long-legged, brown or gray, often with stripes, spots, or banded legs |
| Example size | Female dark fishing spiders: 15–26 mm body length; males: 7–13 mm (excluding legs) |
| Habitat | Freshwater margins, wetlands, streams, wooded areas, and sometimes buildings |
| Diet | Mostly insects and other invertebrates; some species also catch tadpoles or small fish |
| Risk to people | Low; bites are uncommon but may be painful if a spider is trapped or handled |
What Does a Fishing Spider Look Like?
A typical fishing spider has a relatively flattened body, long legs, and mottled brown, gray, or tan coloring. Many species show pale stripes along the head region or abdomen, darker zigzags, or contrasting bands on their legs. Such markings provide camouflage against bark, rocks, reeds, and damp soil.
The spiders have eight legs and usually eight eyes. Eye arrangement can help separate them from wolf spiders under magnification, but a quick photograph rarely shows enough detail for a certain identification. A spider’s location and behavior are often just as useful as its color.
How Big Are Fishing Spiders?
Size depends on the species and sex. For the North American dark fishing spider (Dolomedes tenebrosus), Penn State Extension reports a female body length of about 15–26 mm (0.6–1.0 in) and a male body length of 7–13 mm (0.3–0.5 in). Including their extended legs, large individuals may span approximately 3–3.5 inches (7.6–8.9 cm).
Body length is not leg span. A spider that looks palm-sized with its legs spread out may have a body only an inch long. Avoid applying one species’ measurement to every fishing spider worldwide.
Where Do Fishing Spiders Live?
Many fishing spiders inhabit freshwater edges: ponds, marshes, lakes, drainage channels, and streams. They wait on floating leaves, wet stones, dock posts, vegetation, and partly submerged wood. Different species favor different environments, including quiet ponds or faster-flowing streams.
Not every fishing spider lives directly beside water. The dark fishing spider is frequently found in wooded areas, on tree trunks or logs, under loose bark, and around buildings. It can turn up in a basement or garage far from a visible pond. Such a sighting does not necessarily mean a house has a persistent spider population.
In North America, species of Dolomedes occur across many regions of the United States and Canada. Other members of the genus occur in Europe, Asia, and elsewhere. Geography is important: a species common beside a North American pond should not automatically be used to identify a similar-looking spider in another country.
How Can Fishing Spiders Walk on Water?
Water has a surface tension that can support small animals when their weight is distributed effectively. Fishing spiders take advantage of this with long legs and water-repellent hairs. They can move across the surface without immediately sinking, using rowing or faster running movements depending on the species and situation.
Rather than spinning a web to trap dinner, a fishing spider often waits almost motionless at the water’s edge. Its front legs may touch the water while the rest of its body stays on a plant, rock, or bank. Sensitive hairs and other sensory structures detect ripples created by struggling insects or other small animals. The spider then lunges toward the source.
Can Fishing Spiders Breathe Underwater?
Some species dive to escape danger and can remain submerged for extended periods. Water-repellent body hairs can trap a thin layer of air around the spider. That does not make them fish, nor does it mean every species can remain underwater for the same length of time. Diving ability varies, and the duration depends on conditions.
Most fishing spiders should be understood as semi-aquatic or terrestrial hunters, not animals that live permanently underwater.
What Do Fishing Spiders Eat?
Fishing spiders are predators. Their usual meals are insects and other small invertebrates found on land, in vegetation, or on the water’s surface. Aquatic insects and insects that accidentally fall into water can be especially accessible prey.
The remarkable part is that some fishing spiders can also capture tadpoles, small fish, and other small aquatic vertebrates. These catches are documented, but they should not be presented as the everyday diet of every Dolomedes species. Their food varies with habitat, prey availability, and spider size.
They hold captured prey with their legs and mouthparts and inject venom to immobilize it. Like other spiders, they use digestive fluids to break down prey before consuming it. Fishing spiders therefore play a role in regulating populations of small animals in freshwater-edge and woodland ecosystems.
Common Fishing Spider Species and Lookalikes
Dark Fishing Spider (Dolomedes tenebrosus)
This large, gray-brown North American species often has banded legs and contrasting marks on its abdomen. It is particularly notable for occurring on trees and near houses, sometimes well away from water.
Six-Spotted or Spotted Fishing Spider (Dolomedes triton)
Often seen on quiet freshwater surfaces, this species commonly shows pale borders along the carapace and small light spots on its abdomen. The common name can be confusing: the six spots traditionally referenced are on the underside of the body, not simply six visible spots on the back.
Striped Fishing Spider (Dolomedes scriptus)
Often associated with streams, this species may rest along banks with its front legs touching the water. Distinguishing it from similar brown fishing spiders may require multiple views and regional expertise.
Raft Spiders
“Raft spider” is another common name used for certain Dolomedes species, particularly in Europe. The name is not a separate biological family. For a related example, see our raft spider guide.
Fishing Spider vs. Wolf Spider
Fishing spiders and wolf spiders may both be large, brown, fast-moving hunters. Neither needs a typical prey-catching orb web, so simply seeing a spider without a web is not enough to distinguish them.
- Fishing spiders: Often have long, widely spread legs; many species live near water and detect ripples at the surface.
- Wolf spiders: Usually hunt on the ground; their eye arrangement features two noticeably large central eyes above a lower row of smaller eyes.
- Both groups: Vary considerably in size and pattern, and neither should be identified confidently from size alone.
If you are unsure, compare multiple characteristics in our common spider identification guide.
Reproduction, Egg Sacs, and Life Cycle
Fishing spiders do not use large capture webs to hunt, but silk is still essential to reproduction. After mating, a female creates an egg sac and carries it with her mouthparts. As hatching approaches, she builds a protective nursery web in vegetation or another suitable sheltered place.
When the young emerge, the female may remain close to the nursery for a time. Egg numbers vary substantially among species and individuals, so one universal clutch size is misleading. Spiderlings eventually disperse and pass through successive molts before adulthood.
The timing of mating, the number of egg sacs, and the life span also vary by species and climate. Accounts of males dying during mating describe particular species or observations; they should not be treated as a rule for all fishing spiders.
Do Fishing Spiders Bite? Are They Dangerous?
Fishing spiders are venomous to their prey, but they are not generally considered medically dangerous to humans. They typically flee when approached and usually bite only when trapped, squeezed, or handled. A confirmed bite may cause localized pain, redness, or swelling. Rare sensitivities and complications are possible.
For a suspected minor bite, wash the area gently with soap and water and apply a cool compress. Do not squeeze the wound or attempt to remove venom. Seek prompt medical advice if the pain is severe or worsening, the area develops expanding redness or an open wound, or you are uncertain what caused the injury. Difficulty breathing, swelling of the face or throat, fainting, or other serious systemic symptoms require emergency care.
Many unexplained skin lesions are incorrectly attributed to spiders. Unless a spider was actually seen biting, the cause of a mark often cannot be confirmed from appearance alone.
What Should You Do If You Find a Fishing Spider Indoors?
A large spider in the bath, basement, garage, or next to a door can be startling, but a single sighting is not evidence of an infestation. Dark fishing spiders in particular may wander into buildings from surrounding wooded habitat.
To relocate one, avoid touching it directly. Place a clear container over the spider, carefully slide stiff paper beneath it, and release it in an appropriate sheltered outdoor spot where conditions are suitable. If the species is uncertain, do not handle it with bare hands.
To reduce unwanted encounters, repair window screens, close gaps around exterior doors, and keep stored items tidy. Address persistent indoor moisture when appropriate, but there is no reason to drain a pond or damage wetland habitat simply because fishing spiders live nearby.
Fishing Spider FAQs
Can fishing spiders really catch fish?
Yes. Small fish have been recorded as prey for some Dolomedes species, although insects and other invertebrates are usually more routine meals.
Do fishing spiders make webs?
They make silk egg sacs and nursery webs, but they do not normally depend on prey-catching webs for food. A random sheet web near water is not reliable proof of a fishing spider infestation.
Do fishing spiders jump or swim?
Many can move rapidly across water, sometimes in a hopping or galloping motion, and some can dive beneath the surface. Their exact abilities vary by species.
Are fishing spiders poisonous?
The precise word is venomous, because spiders inject venom through their fangs. Most fishing spider bites are not considered medically significant, but bites can still hurt.
Are fishing spiders aggressive toward people?
Generally no. They tend to escape rather than confront people. Avoid trapping or handling them, especially when an identification is uncertain.
Why is there a fishing spider far from water?
Not all species are strongly aquatic. Dark fishing spiders often occupy wooded places and may wander onto buildings even without a nearby pond or stream.
Final Thoughts
Fishing spiders are remarkable hunters, but their most impressive adaptation is not simply their size. It is their ability to interpret movement at the boundary between land and water. Whether you encounter a water-running Dolomedes beside a pond or a dark fishing spider on a tree trunk, careful observation is more useful than alarm. Give it space, avoid bare-handed handling, and enjoy a glimpse of an unusually capable predator.
References and Editorial Notes
Research consulted: World Spider Catalog, Dolomedes genus and Dolomedidae classification; Penn State Extension, Fishing Spider (updated 2026); Missouri Department of Conservation, Spotted Fishing Spider and Striped Fishing Spider; Yu and colleagues, Systematics and Evolutionary History of Raft and Nursery-Web Spiders (2025); Frontiers in Arachnid Science, Dolomedes Fishing Spider Biology: Gaps and Opportunities for Future Research (2024/2025); Mayo Clinic, Spider Bites: First Aid (2026).
Identification note: The original article images are retained as provided. Their descriptive captions do not claim a verified species-level identification. Image licensing and attribution should be checked in the site’s media library before republication, especially for the file whose name begins with “licensed-image.”
