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Bichir

The bichirs and reedfish (also called ropefish) compose the Polypteridae, a family of archaic-looking ray-finned fishes and the sole family in the order Polypteriformes. All species occur in freshwater habitats in tropical Africa and the Nile River system, mainly swampy, shallow floodplains andestuaries. Bichirs are elongated fish with a unique series of dorsal finlets which vary in number from seven to 18, instead of a single dorsal fin. Each of the dorsal finlets has bifid (double-edged) tips, and are the only fins with spines; the rest of the fins are composed of soft rays. The body is covered in thick, bonelike, and trapezoidal (ganoid) scales. Their jaw structure more closely resembles that of the tetrapods than that of the teleost fishes. Bichirs have a number of other primitive characteristics, including fleshy pectoral fins superficially similar to those of lobe-finned fishes. They also have a pair of slit-like spiracles used to exhale air, two gular plates, and paired ventral lungs (the left lung shorter than the right). Four pairs of gill arches are present. Bichirs have a maximum body length of 97 centimetres (38 in).

Bichir

Betta

Both male and female Bettas basically have the same anatomy. Both have a cylindrical form, with the anterior part of the body tapering to a laterally compressed shape. The pelvic fins are quite long and extended, particularly in the male. The dorsal fin inserts behind the midpoint of the back, and varies in length from short to moderate. In domesticated male Betta splendors, this fin can be exaggerated into a huge sail. Near the pectoral fin insertion, the anal fin is long and when splayed, it billows out like a large fan, in the same way as the caudal fin. When at rest, both fins hang down, giving the appearance of long folded drapes. As a Betta ages, his tail and fins grow longer and heavier, causing him to become sluggish. He will become rejuvenated following what is referred to as 'blowing his tail.' He loses it only to have it grow back with some discoloration and unevenness. However, the loss of the heavy tail rejuvenates him. The beard, which is the membrane under the gill plate cover, is displayed by both male and female when flaring, although the female's is considerably smaller. Without having the ability to blink, the Betta's eyes protrude. Their mouths are particularly interesting. With rows of tiny pointed teeth and powerful jaws, they are perfectly designed and positioned to both devour and to blow bubbles. Proportionately, Bettas have bigger and strong jaws than the great white shark! What is further intriguing about them is the way the males gently carry the eggs in their mouths without damaging them on their sharp teeth.

Betta

Bengal Danio

The Bengal danio or Sind danio, Devario devario, is a subtropical fish belonging to the minnow family (Cyprinidae). Originating in Pakistan,India, Nepal, Bangladesh, and Afghanistan, this fish is sometimes found in community tanks by fish-keeping hobbyists. It grows to a maximum length of 4.0 inches (10.0 cm). In the wild, the Bengal danio is found in rivers, ponds, and fields in a subtropical climate and prefer water with a 6.0 - 8.0 pH, a water hardness of 5.0 - 19.0 dGH, and an ideal temperature range of 59 - 79 °F (15 - 26 °C). Their diet consists of annelid worms, small crustaceans andinsects. The Bengal Danio is an egglayer.

Bengal Danio

Beardfish

The beardfishes consist of a single extant genus (Polymixia) in a small family (Polymixiidae) of deep-sea marine ray-finned fish named for their pair of long hyoid barbels. At present they are classified in their own order Polymixiiformes, but as Nelson says, "few groups have been shifted back and forth as frequently as this one". For instance, they have previously been classified as belonging to the Beryciformes. They are of little economic importance. They are found in tropical and subtropical waters of the Atlantic, Indian and western Pacific Ocean. They are bottom-dwelling fish, found down to about 800 metres (2,600 ft) depth. Most are relatively small fish, although one species is over 40 centimetres (16 in) in length.