Northern Bluefin Tuna

Thunnus thynnus
( image )

Tuna are the long-distance specialists of the fish world, covering several thousand miles a year on their migrations. They are also among the fastest-swimming fish in the world. Some populations are now endangered as a result of the world demand for tuna meat. Tuna are fish built for speed. Every aspect of their body form is suited to maximum performance in the water. Their body is fusiform (pointed at both ends) with a stiff, sickle-shaped caudal (tail) fin perfect for producing maximum thrust. The bluefin tuna also [Read more]

dorado

(Salminus maxillosus), powerful game fish of the characin family, Characidae, found in South American rivers. The dorado is golden, with red fins and with lengthwise rows of dots on its body, and superficially resembles a salmon. It reaches a length of about 1 m (39 inches) and a weight of more than 18 kg (40 pounds). [Read more]

Pacu

The most diverse community is found in the Amazonian and Guianan forests, where the abundance of water and trees makes life easy. Rivers are the realm of large numbers of invertebrates and fishes, such as pacu (Metynnis), which is a big brownish flat fish, the meat of which is highly valued; coumarou (Curimato), which is a toothless vegetarian fish resembling the marine mullet; electric eel (Electrophorus electricus); pirarucu (Arapaima gigas), which can attain a length of 15 feet and a weight of 200 pounds; and piranha, having teeth so sharp that they can cut through flesh like a razor; as well as a wealth of small fishes, many of which are vividly coloured. The manatees (a chiefly tropical, aquatic, [Read more]

Piranha

Also called caribe or piraya razor-toothed, carnivorous fish of South American rivers and lakes, with a somewhat exaggerated reputation for ferocity.

Most species of piranha never grow larger than 60 cm (2 feet) long. Colours vary from silvery with orange undersides to almost completely black. These common fishes have deep bodies, saw-edged bellies, and large, generally blunt heads with strong jaws bearing sharp, triangular teeth that meet in a scissorlike bite. [Read more]

Catfish

Any of the fishes of the order Siluriformes. Catfishes are related to the characins, carp, and minnows (order Cypriniformes) and may be placed with them in the superorder Ostariophysi. Some authorities, however, consider these groups suborders, rather than a single order, and classify them as the suborders Siluroidea (catfishes) and Cyprinoidea (characins, carp, and minnows) of the order Cypriniformes or Ostariophysi. The name catfish refers to the long barbels, or feelers, which are present about the mouth of the fish and resemble cat whiskers. All catfishes have at least one pair of barbels, on the upper jaw; they may also have a pair on the snout and additional pairs on the chin. Many [Read more]

General features ( fish )

Structural diversity

Fishes have been in existence for more than 450,000,000 years, during which time they have evolved repeatedly to fit into almost every conceivable type of aquatic habitat. In a sense, land vertebrates are simply highly modified fishes, for when fishes colonized the land habitat they became tetrapod (four-legged) land vertebrates. The popular conception of a fish as a slippery, streamlined aquatic animal that possesses fins and breathes by gills applies to many fishes, but far more fishes deviate from that conception than conform to it. For example, the body is elongate in many forms and greatly shortened in others; the [Read more]

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