this article is concerned with the fish from biology. For other meanings of the words fish and fish see fish (term clarifying).
Atlantischer Hering (Clupea harengus)
herring ( Clupea harengus) fishes
Subsection: Bilateria
over trunk: New mouths (Deuterostomia)
trunk: Choir-date (choir DATA)
Unterstamm: Vertebrate animals (Vertebrata)
over class: Kiefermäuler (Gnathostomata)
row: Fish
scientific name

fish (Pisces) are change-warm, almost exclusively vertebrate animals with Kiemen, living in the water. About half of all kinds of vertebrate animalfish are, the oldest well-known fossils are approximately 450 million years old. One differentiates particularly cartilage fish (Chondrichthyes), to which among other things the sharks and skates counts, and bone fish (Osteichthyes), which cover all other fish. Two further Fischtaxa, the tank fish (Placodermi)and the prick sharks (Acanthodii), became extinct.

The Forschungsgebiet concerned with fish is called Ichthyologie.

Table of contents

Körperbau und -funktionen


Die Körperform der Fische ist je nach Lebensweise mehr oder weniger lang gestreckt - schnelle Schwimmer sind torpedoförmig, bodenlebende Arten abgeplattet, Arten die in Riffen oder Tangwäldernleben,laterally squeezed together. The size of attained full growth fish varies, depending upon kind, between hardly more than one centimeter and 18 meters.

Building of bones

black point reef shark

the skeleton consists of cartilage (cartilage fish) or bone (bone fish). At the head is the Kiemenskelettfrom four to seven Kiemenbögen, by which the front is reshuffled to the lower jaw. The spinal column is connected with the head. In the trunk region the eddies also lay ribs on, over the whole length of thorn extensions on the back side, within the tail rangethe ventral side. In the muscle sheaths from bone fish are frequently fishbones from verknöchertem connective tissue. For the control and progressive movement serve the fins, which are strengthened up to the Fettflossen (with salmon, Salmlern, Welsen) with knochigen fin jets (radii).Chest and pelvic fins are in pairs and with the shoulder and/or - basin belts connected. The unmatched backs, tail and anal fins grew together over fin carrier (radial one) with the spinal column. The Fettflossen convenient with some kinds between moving and Schwanzflossen have noneSkeleton, can be horn-like strengthened however. For progressive movement - together with a laterally schlängelnden body movement - above all the Schwanzflosse serves. Some kinds move themselves however also predominantly by means of the Brustflossen and use the Schwanzflosse only as rudders.


The skin of the fish consists of two layers: the bindegewebshaltigen leather skin, in which sheds and color cells are, and which with Schleimdrüsen provided Oberhaut. The Schleim reduces flow resistance, since it raises the critical speed for the emergence of turbulences. Of theThe Fischschleim has further ones a protecting effect on the sheds and the underlying skin, since it works antibacterially. With cartilage fish tiny, tooth-like Placoidschuppen takes over a comparable function.

Cycle and respiration

of fish have a closed Blutkreislauf with close to that Kiemen convenient, simple heart, which consists of a forecourt and a Herzkammer. It pumps venous blood directly to the Kiemen, which exist fine skin from inverting of numerous , with capillaries durchzogenen lamellas. The Kiemen takes loosened oxygen over its large surfacefrom the water up and pass on it to the blood. The very high effectiveness of the oxygen admission over the Kiemen (up to 70% of the available oxygen) can on the principle of the counter current exchanger in the Kiemen and the very high affinityfrom some fish hämoglobinen to oxygen to be led back. With bone fish the Kiemenspalten are covered by horn-like Kiemendeckel (Operculum). By the sinking of the mouth soil and simultaneous taking of the Kiemendeckels off it comes to an influx of water by the muzzle. Diaphragmsat the Kiemendeckeln prevent an influx of the water. When pressing out a flap and the water close by the Kiemenspalten are to the rear pressed out within the front muzzle range. Cartilage fish, whose Kiemenspalten are from the outside visible, must itself against it constantly with openedMuzzle move, so that the water at the Kiemen can flow along.

Fossiler Fisch in Kalkstein
Fossil fish in limestone
Franzosen-Kaiserfisch (Pomacanthus paru)
Frenchman emperor fish (Pomacanthus paru)
draw for Kupferstreifen Pinzettfisch (Chelmon rostratus
Fische zeichnen sich auch durch eine große Formenvielfalt aus
) of fish also by large form variety out

with some bone fish (for example Aalen)the Kiemenhöhle is outward opened only by small gap, whereby the Kiemen remains also on the dry one a certain time damp and thus functional. Some more or less amphibiously living fish types have further respiratory organs: Mud Springer know atmospheric oxygentake up by skin respiration. More common the intestine respiration , for example with the Schlammpeitzger , is air is swallowed, the gas exchange takes place at the walls of the strongly supplied with blood front intestine. Some fish (labyrinth fish) breathe also air, by them Ausstülpungen in the head areause for the admission of oxygen from air. Like the Knochenhechten, also the swimming blister serves fish, whose swimming blister is connected with the intestine still , for the air respiration. With Flösselhechten and lung fish these intestine from inverting already developed to lungs.

Swimming blister

With most fish types the swimming blister has the function to adjust the specific weight ( the density) so that they can to float without effort of force in the water or sink only very slowly to soil. Came out it from a Ausstülpung onthe top side of the intestine entrance; it can, as connected with the carps, still with it its (physiostom) or, as with the Bar chambers separated from the intestine form (physioklist). The adjustment of the specific weight gases (oxygen, carbon dioxide become, Nitrogen) from the blood over the gas gland in such a way specified or a connecting corridor to the intestine, ductus pneumaticus into the swimming blister delivered. At emptying the gas arrives to the swimming blister either over ductus pneumaticus into the front intestine or overa strongly supplied with blood range in the swimming blister wall, the oval, again back in the blood. To cartilage fish, in addition, soil-living or particularly well swimming bone fish is missing the swimming blister - they sink to soil, if they do not move.

Nervous system and sensory organs

that Nervous system is simply, the brain small, a cerebral cortex is missing. The sense of smell of the fish is pronounced much, nose and oral cavity is from each other separated. The ears consist of closed, blisters filled with liquid, with some kinds are them by mobile bones with the swimming blisterconnected. In the structure they resemble the interior ear of humans. Most fish types can notice signals below 1 kHz, some their aural acuity by special structures improved and the audio range to 5 or more kHz extended. The eyes have a rigidLens, which is focused on close view. They notice also ultraviolet light. Particularly with soil-living fish the Tastsinn is well developed. Particularly at lips and Barteln sensory cells in the Oberhaut, which transfer contact attractions, are. As “the sixth sense” orderFish over organs for the perception of water flows, the collateral line organs, which extend laterally for instance in the center over a majority of the body length. They consist those of a set of skin A INVERTINg, in which sensory cells with sensory hairs are, by flow changesare moved.


the reproduction organs of the fish are laterally and above the intestine. Fertilization takes place at most kinds without Kopulation , instead the female Rogen (the eggs) and the male milk (the seed) become about simultaneous inWater set off. The number of eggs varies extremely: Disturb put several millions, the breedingmaintaining Stichlinge no longer than hundreds. With breedingmaintaining kinds there is frequent the males, which take over the care. There are different forms with the breedingmaintaining kinds:Open, excavating and muzzle breeder. Inseminated with open breeders the eggs of the female on plants or other firm materials puts down and afterwards by the male. With cave breeders the eggs at the cover are put down by caves. After slipping the boys becomestill for a while on sheets or into pits put down to the Dottersack used up is. Afterwards the larvae are led by parents, whereby parents alternate either or parents guard, mostly the male the district borders. A majority goesthe brood it lost then it can occur that parents eat and fast again with a new brood begin the few survivors larvae. With muzzle breeders the females take the eggs after the file in the muzzle, the male swim over thoseEggs and delivers thereby his seed. The boys of the muzzle breeders are developed if it the muzzle abandoned already far, them return to slipping however still for a while with danger in the muzzle. So-called Kuckuckswelse specialized in itto give their eggs to the eggs of the landlord fish, which are then taken up by the female also to the muzzle and expenditure-bred there. The faster developing Welslarven eats then the eggs or larvae of the landlord fish. Diskusfi separate after slipping inHautsekret off, which is grazed by the larvae and as Erstnahrung serves. With labyrinth fish the males form a foam nest frequently at the water surface between swimming plants and drive then the female to the oviposition under the foam nest. The male loops alsoits body and it turns the female on the backs, so that the eggs swim upward. After inseminating the female is driven out and the brood of the male alone protected to the larvae to slip, afterwards also that worriesMale not further around the brood. Some fish types do not have genetically determined sex, it mint themselves only by the contact with partners or by environmental condition and can several times be changed. There are also fish, which have Kopulationsorgane, howfor example sharks. Such fish are frequent living-bearing.


the female fish capable of the reproduction is called Rogner, the reproductionable male fish Milchner is called.


the fish it are a paraphyletisches Taxon, that means that the group of not allDescendants of the common ancestor of all fish covers. The land vertebrate animals ( Tetrapoda) are missing, which actually represent a sub-group of the bone fish. Like that for example the Quastenflosser and lung fish are related to the land vertebrate animals more closely than with other fish. From kladistischer view are the fish therefore no valid Taxon more, since according to this method only monophyletische groups are recognized and designated. The Wikipedia follows here however traditional systematics. The fish let themselves be defined then best as Ausschlusstaxon: Fish are all Kiefermäuler, which are not land vertebrate animals.

In principle to the fish the Kieferlosen ( Agnatha) does not belong, as for example the nine-eyes, which are nevertheless sometimes called in the popular linguistic usage “fish”.

Mosaik im Nationalmuseum Neapel
Mosaic in the national museum Neapel

cultural meaning

the fish becomes in the Christianity as symbol Jesu Christi uses. Often the name with the letters of the Greek word for fish (Ichthys) is interpreted: J (esus) CH (ristos) Th (eou) Y (ios) S (more oter) (dt. „Jesus Christ, God son, the Erlöser “).

See fish (Christianity)

in economic regardthe fishery, in addition, the trade with Zierfi are important. Both can threaten however the fish existence, which in addition also by the introduction by pollutants into their habitat are endangered; a too strong load can lead to fishing inheriting. Upthe ecological endangerment of the fish is to make regular proclaiming attentive per for a kind as a fish of the yearly.

See also: Systematics of the cartilage fish, systematics of the bone fish


  • K. A. Frickhinger: Mergus fossil Atlas of fish. A bibliophile and ichthyologische preciousness,Mergus publishing house 1991
  • H. Gebhardt, A. Ness: Fish, BLV publishing house, Munich, 2005. ISBN: 3-405-15106-6.

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