Arapaima Fish

The Arapaima fish is also known as the Pirarucu, and is one of the biggest freshwater fish species in the world. Its scientific name is Arapaima gigas. This fish can only be found wild in the Amazon River Basin in South America. It can reach a length of 450 centimeters (177.17 inches) and weigh up to 200 kilograms (440 lbs). The Arapaima is grey and decorated with an orange speckling at the posterior end. The scales can grow up to six centimeters long on the largest Arapaima specimens. You will find two symmetrical fins on the body, located at the posterior end.

The Arapaima can be kept in aquariums, but you must of course be prepared to provide your Arapaima with larger and larger aquariums as it grows. A 450 centimeter long Arapaima is of course very impractical to keep for most aquarists. Since the Arapaima is near extinct in some parts of South America, you should choose your specimen carefully. Purchase a captive breed Arapaima or make sure that is has been caught in an area where it is not endangered.

The Arapaima is a very popular food fish in South America and it is also admired among sport fishers. More than 50 percent of the total body weight of this fish is made up by meat, and the meat is boneless, a fact which makes it even more popular as food. The bony tongue is used to prepare cylinders of dried guarana, while the scales are sold as nail files. (Guarana is an ingredient used in a South American beverage.) A majority of the caught Arapaima fishes are sold and consumed in Brazil. Arapaima harvesting is today forbidden in many regions, e.g. Guyana, but the illegal fishing still continues.

Over fishing has made it hard to find large Arapaima specimens. Once upon a time, there were a lot of Arapaima fishes weighing over 150 kilograms and measuring more than 3 meters in length. More than 30 years of over fishing have now drastically reduced the amount of large Arapaima fishes in South America, and has had a severe effect on the entire Arapaima population as well. The Arapaima fish is usually netted or harpooned.

The Arapaima is a predatory fish that eats fish, birds and any other animal that it can catch. The major part of its diet consists of fish, but since it is a large opportunistic hunter it will happily gulp down other animals as well. Arapaimas prefer to hunt close to the surface since they need to breathe oxygen from the air. This does however not prevent the Arapaima from occasionally diving very far down. The fact that this fish needs to breathe air from the atmosphere every 10-20 minutes must of course be taken into consideration if you intend to keep an Arapaima in captivity. The aquarium must be arranged in a way that makes access to fresh air possible.

Arapaima is found in various habitats in the Amazon River Basin which means that you can have some freedom when you decorate its aquarium. You will find Arapaima in the Amazon River, in the tributaries and in the floodplain lakes. It lives in white water as well as clear water, and the fact that it breaths oxygen from the atmosphere makes it possible for this fish to live in oxygen depleted swampy waters as well.

The Arapaima is an egg-laying mouth-brooding species that tend to its eggs as well as its larvae. Since Arapaima fish sometimes inhabit oxygen depleted waters, they will aerate the water to make sure that the eggs get enough oxygen. Adult fish can communicate with their offspring by exuding a special pheromone from the head. The pheromone makes the larvae stay close to their parents where they can be protected from predators.

The reproductive cycle of Arapaima fish depend on the seasons, and the female will lay eggs in February, March or April. During this period, the water levels in the Amazon River Basin are very low. The eggs are placed in a nest that has been built by the parents at the bottom. This nest is usually around 50 centimeters in diameter and 15 centimeters deep. When the eggs hatch, the flooding season is well on its way in the Amazon River Basin and the offspring can feast on an abundance of small aquatic organisms.

source : http://www.aquaticcommunity.com, youtube

Oarfish

Oarfish are large, greatly elongated, pelagic Lampriform fishes comprising the small family Regalecidae. Found in all temperate to tropical oceans yet rarely seen, the oarfish family contains four species in two genera. One of these, the king of herrings (Regalecus glesne), is listed in the Guinness Book of World Records as the longest bony fish alive, at up to 17 metres (56 ft) in length.

The common name oarfish is presumably in reference to either their highly compressed and elongated bodies, or to the former (but now discredited) belief that the fish "row" themselves through the water with their pelvic fins. The family name Regalecidae is derived from the Latin regalis, meaning "royal". The occasional beachings of oarfish after storms, and their habit of lingering at the surface when sick or dying, make oarfish a probable source of many sea serpent tales.

Although the larger species are considered game fish and are (to a minor extent) fished commercially, oarfish are rarely caught alive; their flesh is not well regarded due to its gelatinous consistency.

Anatomy and morphology

The tapering, ribbony silver bodies of oarfish—together with an impressive, pinkish to cardinal red dorsal fin—help explain the perception of majesty taken from rare encounters. The dorsal fin originates from above the (relatively small) eyes and runs the entire length of the fish. Of the approximately 400 dorsal fin rays, the first 10 to 12 are elongated to varying degrees, forming a trailing crest embellished with reddish spots and flaps of skin at the ray tips. The pelvic fins are similarly elongated and adorned, reduced to 1 to 5 rays each. The pectoral fins are greatly reduced and situated low on the body. The anal fin is completely absent and the caudal fin may be reduced or absent as well, with the body tapering to a fine point. All fins lack true spines. At least one account, from researchers in New Zealand, describes the oarfish as giving off "electric shocks" when touched.

Like other members of its order, the oarfish has a small yet highly protrusible oblique mouth with no visible teeth. The body is scaleless and the skin covered with easily abraded, silvery guanine. In the streamer fish (Agrostichthys parkeri), the skin is clad with hard tubercles. All species lack gas bladders and the number of gill rakers is variable.

Oarfish coloration is also variable; the flanks are commonly covered with irregular bluish to blackish streaks, black dots, and squiggles. These markings quickly fade following death. The king of herrings is by far the largest member of the family at a published total length of 11 meters (with unconfirmed reports of 15 meters or more) and 272 kilograms in weight. The streamer fish is known to reach 3 meters total length whilst the largest recorded specimen of Regalecus russelii measured just 5.5 centimeters standard length. It is probable that this little-known species can regularly reach a maximum length of at least 15.2 meters (50 ft).

Distribution

The members of the family are known to have a worldwide range. However, specific encounters with live individuals in situ are rare and distribution information is collated from records of oarfishes caught or washed ashore.

Ecology and life history

Rare encounters with divers and accidental catches have supplied what little is known of oarfish behavior and ecology. Apparently solitary animals, oarfish may frequent significant depths up to 1,000 metres (3,300 ft). A photograph on display in bars, restaurants, guesthouses, and markets around Thailand that is captioned, "Queen of Nagas seized by American Army at Mekhong River, Laos Military Base on June 27, 1973 with the length of 7.80 meters," is a hoax. The photograph is actually that taken by USN LT DeeDee Van Wormer, of an oarfish found in late 1996 by US Navy SEAL trainees on the coast of Conorado, California.

A catch of an 11 ft 4 in (3.3 metres), 140 lb (63.5kg) monster that turned out to be an oarfish was reported on 17 February 2003 by Ms Val Fletcher, who was using a fishing rod baited with squid, at Skinningrove, a coastal settlement of north-east England.

Behavior

In 2001 an oarfish was filmed alive and in situ: the 1.5 meter fish was spotted by a group of US Navy personnel during the inspection of a buoy in the Bahamas. The oarfish was observed to propel itself via an amiiform mode of swimming; that is, rhythmically undulating the dorsal fin whilst keeping the body itself straight. Perhaps indicating a feeding posture, oarfish have been observed swimming in a vertical orientation, with their long axis perpendicular to the ocean surface. In this posture the downstreaming light would silhouette the oarfishes' prey, making them easier to spot.

In July 2008, Canadian Researcher William Sommers captured footage of the rare fish swimming in its natural habitat off the Gulf of Mexico. It is the first ever confirmed sighting of an oarfish at depth, as most specimens are discovered dying at the sea surface or washed ashore. The fish was estimated to be between 5m and 10m in length.

From December 2009 through March 2010, unusual numbers of the slender oarfish Regalecus russelii (竜宮の使い “Ryūgū-No-Tsukai”,) known in Japanese folklore as the Messenger from the Sea God's Palace, have appeared in the waters and on the beaches of Japan; the appearance of which is said to portend earthquakes.

Feeding Ecology

Oarfish feed primarily on zooplankton, selectively straining tiny euphausiids, shrimp, and other crustaceans from the water. Small fish, jellyfish, and squid are also taken. Large open-ocean carnivores are all likely predators of oarfish, and include the Oceanic whitetip Shark. Oarfish have no visible teeth.

Life history

The oceanodromous Regalecus glesne is recorded as spawing off Mexico from July to December; all species are presumed to be non-guarders and release brightly coloured, buoyant eggs, up to 6 millimetres (0.24 in) across, which are incorporated into the zooplankton. The eggs hatch after about three weeks into highly active larvae, that feed on other zooplankton. The larvae have little resemblance to the adults, with long dorsal and pelvic fins and extensible mouths. Larvae and juveniles have been observed drifting just below the surface. In contrast, adult oarfish are rarely seen at the surface when not sick or injured.



source : http://en.wikipedia.org, Youtube

Moray Eel

Moray eels are cosmopolitan eels of the family Muraenidae. The approximately 200 species in 15 genera are almost exclusively marine, but several species are regularly seen in brackish water and a few, for example the freshwater moray (Gymnothorax polyuranodon) can sometimes be found in freshwater. With a maximum length of 11.5 centimetres (4.5 in), the smallest moray is likely the Synder's moray (Anarchias leucurus), while the longest species, the slender giant moray (Strophidon sathete) reaches up to 4 metres (13 ft). The largest in terms of total mass is the giant moray (Gymnothorax javanicus), which reaches almost 3 metres (9.8 ft) and can weigh over 36 kilograms (79 lb).

Anatomy

The dorsal fin extends from just behind the head along the back and joins seamlessly with the caudal and anal fins. Most species lack pecktoral and pelvic fins, adding to their serpentine appearance. Their eyes are rather small; morays rely on their highly developed sense of smell, lying in wait to ambush prey.

The body is generally patterned. Camouflage is also present inside the mouth. Their jaws are wide, framing a protruding snout. They possess large teeth, designed to tear flesh as opposed to holding or chewing.

Moray eels' heads are too narrow to create the negative pressure that most fish use to swallow prey. Quite possibly because of this, they have a second set of jaws in their throat called pharyngeal jaws, which also possess teeth. When feeding, morays launch these jaws into the mouth, where they grasp prey and transport it into the throat and digestive system. Moray eels are the only animal that uses pharyngeal jaws to actively capture and restrain prey. Larger morays are capable of seriously wounding humans.

Morays secrete a protective mucus over their smooth, scaleless skin which in some species contains a toxin. Morays have much thicker skin and high densities of goblet cells in the epidermis that allows mucus to be produced at a higher rate than in other eel species. This allows sand granules to adhere to the sides of their burrows in sand-dwelling morays, thus making the walls of the burrow more permanent due to the glycosylation of mucins in mucus. Their small circular gills, located on the flanks far posterior to the mouth, require the moray to maintain a gap in order to facilitate respiration.

Morays are carnivorous and feed primarily on other fish, cephalopods, mollusks, and crustaceans. Groupers, other morays, barracudas and sea snakes are among their few predators. There is a commercial fishery for several species, but some cause ciguatera fish pois ciguatera fish poisoning. Morays hide in reef crevices until their prey is close enough for capture. They then lunge out and clamp the prey in their strong jaws.

Cooperative hunting

A species of reef-associated grouper, the roving coral grouper (Plectropomus pessuliferus), have been observed to recruit morays to aid them while hunting for food. This is the only known instance of interspecies cooperation among fish.

Reputation

The Morays have sometimes been described as vicious or ill-tempered. Morays hide from humans and would rather flee than fight. Morays are shy and secretive, and attack humans only in self-defense or mistaken identity (for example, a finger placed in a crevice where a moray resides may resemble a prey-item). Most attacks involve accidental bites during human-initiated interaction. Morays cannot see very well and rely mostly on their acute sense of smell. Morays, however, do inflict a nasty bite, and while the majority are not believed to be venomous, circumstantial evidence suggests that a few species may be.

Eels that have eaten certain types of toxic algae or fish that have eaten some of these algae can cause ciguatera fish poisoning if eaten. Large morays can also cause extreme physical trauma, in some cases removing an incautious diver's finger. Morays rest in crevices during the day and hunt nocturnally, although they may ensnare small fish and crustaceans that pass near them during the day.

Habitat

Moray eels are cosmopolitan, found in both tropical and temperate seas, although the largest species richness is at reefs in warm oceans. Very few species occur outside the tropics or subtropics, and the ones that do only extend marginally beyond these regions. They live at depths of up to several hundred metres, where they spend most of their time concealed inside crevices and alcoves. While several species regularly are found in brackish water, very few species can be found in freshwater, for example the freshwater moray (Gymnothorax polyuranodon) and the pink-lipped moray eel (Echidna rhodochilus).


source : http://en.wikipedia.org, Youtube