The Archerfish is a small Asian fish whose most noted method of hunting insect prey is by shooting it out of the air or from vegetation with an extremely accurate jet of water, propelled from the mouth.
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Family: Toxotidae
Genus: Toxotes
Species: 6 species in total, listed below
Archerfish can be found in the waters of
India,
South-East Asia and
Northern Australia. They generally dwell in
brackish water such as
mangrove estuaries, but will also survive in
fresh water and often make their way up coastal rivers and streams. They can also exist around
reefs.
The fish can grow to around 30 cm long, but are usually smaller. They’re narrow bodied, perch-like fish (hence the order “Perciformes”) with eyes and mouth very close to the top of their body. Colouring is usually darker on top, silver on the underside, for maximum camouflage. Patterns and colours depend on species, region and environmental factors. They are often banded with black and yellow vertical stripes. There is little or no sexual dimorphism, and individuals appear to become less colourful with age.
Archerfish are edible, and are sold fresh in many Asian markets. They are captured extensively for the pet market (admit it – you want one…) and the genus is becoming endangered by this over-fishing, and through the destruction of mangroves.
Breeding adults are believed to swim out to reefs to lay eggs – in batches of about 20,000-150,000. Only a few will survive to maturity – though growth is fairly quick, with mature size being reached in around two years. The fish are bred in captivity, so if you buy one, make sure it’s captive bred if you possibly can.
Splut! You're dead!
Archerfish are insectivorous (and won’t say no to smaller fish and crustaceans, either), and they have several methods of hunting. They will leap from the water to grab an insect out of the air, or catch smaller fish or insects in the water. Insects on the top of the water will be snapped up from below.
The method that got the archerfish its name, though, is its unique strategy of shooting a highly accurate stream of water at an insect flying above the water, or perched on overhanging vegetation. If the archerfish is on its own, it will usually wait for the stunned/waterlogged/off balance insect to hit the water, then snap it up. If, as is often the case, the archerfish is part of a small school, the members of the shoal will leap out of the water to attempt to catch the insect mid-fall.
How do they do it?
Glad you asked. Their upper palate is grooved, and the jet of water is produced by pressing the tongue to the upper mouth – making a tube, then snapping the gills shut. This forces the jet of water out the archerfish’s mouth. In order to avoid refraction problems, the fish often shoots from directly below the insect, though I have seen very accurate shooting at an angle of about 60º from the horizontal. They appear able to allow for refraction, and for the curvature of their water jet – though these are learned rather than instinctive abilities. Archerfish are accurate shooters up to about 1.5 metres, and the jet can travel to around 3 metres. They can spit up to 7 times in quick succession. Fish as small as 2-3 cm in length are able to spit, but only with a range of around 10cm.
Keeping Archerfish:
Archerfish are extremely popular aquarium pets due to their funky shooting abilities. They’re also quite attractive and easy to keep. They can be kept in freshwater, though slightly brackish water is recommended for their ongoing health. Brackish water is about 1 tablespoon of salt to every 5 gallons of water, but for the true enthusiast a measure of water density is far more accurate. The water should be fairly hard, and slightly alkaline. Archerfish will live for around 5-10 years with care.
An Archerfish aquarium should be fairly large, with no metal parts in contact with the water (beware rust). Temperature should be maintained at 25-30ºC (77-86ºF). The ideal aquarium should be tall – with a good metre of space between the water and the lid, for branches and vegetation. This will allow you to introduce insects to the aquarium, and watch them being shot down. Endless entertainment there.
Archerfish can be kept with other fish – either of their own genus or other varieties. However, all the fish should ideally be around the same size, to avoid bullying and in extreme cases, eating of other fish. Feeding Archerfish is easy. A good diet is freeze dried bloodworms, small live fish, live crickets, and other such dainties.
Nomenclature:
Also called the Siamese Archerfish, or Ikan Sumpit in Malay. Can be referred to as “Archer Fish” (by such experts as Webster 1913, “Archer-fish” (Gerald Durrell) or “Archerfish” (World Book encyclopaedia). I like the latter choice. The genus name “Toxotes” means “archer” or “bowman”.
Archerfish spp:
Toxotes jaculatrix (Banded Archerfish) Sometimes listed as Toxotes jaculator
Toxotes chatareus (Largescale Archerfish, Seven-spot Archerfish)
Toxotes lorentzi (Primitive Archerfish, Lorentz’s Archerfish)
Toxotes oligolepsis (Western Archerfish) Sometimes listed as Largescale Archerfish
Toxotes microlepsis (Smallscale Archerfish)
Toxotes blythii
Acknowledgements:
http://www.nativefish.asn.au/taxonomy.html
http://www.fishbase.org
http://www.aquariumfish.net/catalog_pages/brackish_water/archer_fish.htm
http://www.naturia.per.sg/buloh/verts/archer_fish.htm
http://www.thetropicaltank.co.uk/Fishindx/archerf.htm
http://www.users.bigpond.com/rjeb/archer.html