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Fish-Distribution and Habitat
Suggested Readings
Taxonomy and Classification of fish
Distribution and Habitat
Morphology of fish and Body parts
Food Habits of Fish
Camouflage in Fish
Communication and Perception in Fish
Life stages and Breeding in Fish
Effect of Fish on Ecosystems
Conservation and Threat







Fishes are normally present wherever there is a body of water, even if it dries for some time of the year.

Fishes inhabit a variety of extreme environments. these include high altitude lakes and streams, desert springs (e.g. pupfishes), subterranean caves (e.g. cavefishes), ephemeral(temporary0 pools, polar seas, and the depths of the ocean (e.g. deepsea anglerfishes).

Across these habitats water temperatures may range from -1.8 C to nearly 40C, pH levels from 4 to 10+, dissolved oxygen levels from zero to saturation, salinities from 0 to 90 parts per million and depths ranging from 0 to 7,000 m (Davenport and Sayer 1993 in Moyle and Cech 2004:1)

Some fish even spend considerable time outside of water: mudskippers prey on the invertebrates of mudflat habitats, while air breathing catfishes and gouramies live in stagnant, low oxygen ponds (among other habitats) or migrate over land to colonize new areas.

Another extreme example of habitat adaptation is found in hillstream loaches , which live in the steep, torrential watercourses of Asiatic hillstreams. Hillstream loaches have flattened bodies and utilize suckers, permanently clinging to rock faces so they are not swept downstream.

Lanternfishes , hatchetfishes , dragonfishes , deep-sea codfishes , halosaurs and spiny eels all have lights (flashing or constant), created by luminescent bacteria or special glandular cells, to find prey, communicate with other individuals, or for defence in the blackness of their deep sea habitats

Disparate localities may have similar geographic conditions, yet fish species composition varies widely across similar regions.
In other words, patterns of fish distribution are not simply related to how well a fish is adapted to a particular type of environment, which is why invasive species can be so devastating.

There is a branch of science called “zoogeography”, it attempts to answer questions about how and why fish (and other animal) faunas differ across geographic locations





Fishes can be broadly divided into two categories depending upon the type of water they live in, they can be classified as Freshwater and Marine.

Freshwater fish can be further divided into Primary and Secondary.

Primary Fish spend all their life in freshwater and cannot tolerate any salinity, angels and goldfish are such examples.

Secondary or Peripheral (euryhaline) fish can tolerate a wide amount of salinity. Many gobies , perches fall in this category.

Some Secondary fish migrate beween freshwater and sea and are called “diadromous” .

Some live in sea and migrate to freshwater for spawning and are called “anadromous”,like salmon and lampreys.

On the other hand, some live in freshwater and migrate to sea to spawn and are called “catadromous”. Some example are freshwater eels.

Fresh water covers only a tiny fraction of the earth’s surface (.0093 percent), yet it is home to approximately 41 percent of all fish species.

Most of these are concentrated in the tropics (1,500 different species in the Amazon Basin alone), and Southeast Asia probably has the most diverse assemblage of freshwater species.

Indian region alone has 930 freshwater species of fish (Jayaram 1994)

In marine areas, species concentrations are highest around coral reefs, where butterfly fishes and angelfishes , wrasses , parrotfishes and triggerfishes are common.

In the arctic seas five families dominate: thornfishes , plunderfishes, Antarctic dragonfishes , and notothens.




  Sandeep Raghuvanshi
Picture Credits   Wikipdeia and other sources which have released under GNU, unless specifically credited

Nelson, Fish of the world 2006,

Jayaram, Biology of Fish, 1994