FISH Fish are aquatic vertebrates that are typically cold-blooded, covered with scales, and equipped with two sets of paired fins and several unpaired fins. Fish are abundant in the sea and in fresh water, with species being known from mountain streams (e.g., char and gudgeon) as well as in the deepest depths of the ocean (e.g., gulpers and anglerfish). They are of tremendous importance as food for people around the world, either collected from the wild or farmed in much the same way as cattle or chickens. Fish are also exploited for recreation, through angling and fishkeeping, and are commonly exhibited in public aquaria. Fish have an important role in many cultures through the ages, ranging as widely as deities and religious symbols to subjects of books and popular movies. (From Wikipedia, the free encyclopedia)

Conservation
As of 2006, the World Conservation Union or International Union for the Conservation of Nature and Natural Resources (IUCN) Red List describes 1,173 species of fish as being threatened with extinction. Included on this list are species such as Atlantic cod,[Devil's Hole pupfish, coelacanths, and great white sharks. Because fish live underwater they are much more difficult to study than terrestrial animals and plants, and information about fish populations is often lacking. However, freshwater fish seem particularly threatened because they often live in relatively small areas.

Overfishing
In the case of edible fishes such as cod and tuna a major threat is overfishing. Where overfishing persists, it eventually causes the collapse of the fish population (known as a "stock") because the population cannot breed fast enough to replace the individuals removed by fishing. The main tension between fisheries science and the fishing industry is the need to balance conservation with preserving the livelihoods of fishermen. On the other hand, scientists and conservations push for increasingly stringent protection for fish stocks, warning that many stocks could be wiped out within fifty years <

Most Asked Questions About Fish

What is a fish? A fish is an animal which lives and breathes in water. All fish are vertebrates (have a backbone) and most breathe through gills and have fins and scales. Fish make up about half of all known vertebrate species.

What is a person who studies fish called? An ichthyologist.

How are fish identified? A combination of the number of fins and their characteristics, scale counts, general features, colour, maximum length and distribution are used.

What is the difference between male and female fish? In some species the males and females have different shaped bodies or different colouring; in other species there is no visible difference.

How do fish breathe? Some fish have lungs and breathe air, but most breathe through gills. Gills are made up of thin sheets of tissue richly supplied with blood vessels. As water passes over them dissolved oxygen is absorbed into the blood and waste products such as carbon dioxide pass out into the water. The gills are protected by a large bony plate called an operculum.

Why are fish slimy? Fish secrete a type of mucus from their skin. This slime coating is important because it provides protection against parasites and diseases, covers wounds to prevent infection and helps fish move through the water faster. Some species release toxins in their slime which ward off attacking creatures while others use their slime to feed their young.

How do you age fish? Scientists age fish using otoliths, a small, white structure found in the heads of all fish except sharks, rays and lampreys. Not only do otoliths provide fish with a sense of balance and help in hearing, but growth rings called annuli are formed on the otolith everyday. Using a microscope the exact age of a fish can be determined.

What is a lateral line? The lateral line is a row of scales that most fish have along their sides, stretching from their head to tail. Under these scales are a system of fluid-filled canals and specialised cells which transmit vibrations to the brain. The lateral line helps fish to detect objects including predators and prey.

What do fish eat? Detritus, diatoms, algae, zooplankton, fish and their eggs, terrestrial insects, aquatic macro-invertebrates (particularly insect larvae, crustaceans and worms), molluscs, aquatic plants, water birds, turtles, frogs, snakes and mice.

What eats fish? Other fish, birds (e.g. pelicans, cormorants and herons), snakes, turtles, crustaceans, some insect larvae (e.g. dragonfly larvae), and humans. In other parts of the world there are also animals such as wild cats, wild pigs and bears that feed on fish.