Archerfish

Order: Perciformes     Family: Toxotidae    Genus & Species: Toxotes jaculator

Fish that feed on insects usually rely on them either falling, landing or being blown onto the water.  The archerfish however, employs his own unusual technique of catching them.

Habitat The archerfish inhabits river estuaries and coastal creeks where the fresh river water is made salty by the coastal tides.  Twice a day, the river water is slowed by the tide.  Fine silt can then settle on the bottom, forming great mud flats.  At low tide, these mud flats are exposed and, in the northern hemisphere, are colonized by a variety of grasses and develop into salt marshes.  In the tropics they are colonized by mangrove trees and these form the flooded forests known as the mangrove swamps.

Behaviour
The archerfish swims among the roots at high tide and moves out of the swamp as the water level falls.  During low water, the archerfish may travel quite a distance along the coast to investigate new feeding grounds.  It also swims inland up rivers and creeks, but doesn't travel very far.  Probably because its body chemistry is unsuited to life in pure freshwater.  It is most active during the day, when there is enough light to see its prey through the murky swamp water.  At night it has been seen lying motionless among the mangrove roots, which offer some protection from large predators.

How they hunt The archerfish watches from among the submerged roots for any sign of movement that betrays insects landing to rest on the vegetation above the water line.   Its eyes face forward, giving it the binocular vision it needs to judge distance accurately.  When it spots a potential target, it tries to swim directly beneath it to minimize the distortion caused by the way the light is bent as it passes from air to water. Once in range, the archerfish fires a jet of water, knocking the victim off its perch and into its waiting jaws.  It shoots its jet with such force that it stings if it hits human flesh.  They sometimes hunt in groups of four or five, taking turns at shooting.  On other occasions, it does not shoot at an insect, instead it jumps clear of the water to catch it in its mouth.

Breeding Although the breeding habits of the archerfish are still something of a mystery, it is believed that they swim upstream during the rainy season to breed in rivers and backwaters.  This migration is necessary as the rise and fall of the tide in the swamps would expose the eggs to the air twice a day.  As soon as the eggs are deposited by the female, the archerfish swims back downstream towards the sea.

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