Almost all Dolomedes species are semiaquatic, with the exception of the tree-dwelling D. albineus of the southeastern United States.

They hunt by waiting at the edge of a pool or stream, then when they detect the ripples from prey, they run across the surface to subdue it using their foremost legs, which are tipped with small claws; then injecting venom with their hollow chelicerae to kill and digest the prey.

[2] There are over a hundred species of Dolomedes throughout the world; examples include Dolomedes aquaticus, a forest-stream species of New Zealand, the raft spider (D. fimbriatus), which lives in bogs in Europe, and the great raft spider (D. plantarius), which lives in fens, also in Europe.

Dolomedes species tend to be robust with thickset legs that allow them to tackle prey larger than themselves.

To this end they have a range of vibration-detecting organs, including very sensitive hairs (trichobothria) on their legs and feet.

Their eyes play a secondary role; experiments on related species show that touch is the main sense these spiders use to catch their prey.

Fishing spiders' main prey is aquatic insects, but they are opportunistic feeders and will eat anything suitable that happens within range.

However, some wasps, such as Anoplius depressipes, are able to be underwater for a few minutes to sting the spider and drag it out of the water.

Mating in one North American species (D. tenebrosus) always results in the obligate death of the male, with no obvious involvement from the female.

[1] The six-spotted fishing spider (D. triton) lives primarily in small lakes and ponds.

This spider consumes mostly water striders (pond skaters), but like all Dolomedes, it is an opportunistic ambush hunter that will eat anything that it can capture.

[1] The Palearctic raft spider (D. fimbriatus) is widespread on the surface of bog pools and in boggy grassland.

[7] The largest New Zealand species, D. schauinslandi or the Rangatira spider, occurs on rodent-free islands in the Chathams where running water is rare.