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The arapaima is said to be one of the largest fresh water fishes and is often likened to the pike. It's body is long and cylindrical with the unpaired fins set well back toward the tail. The head of this fish is mall and flattened with a jutting lower jaw. The front half of the arapaima is green with the rear half becoming increasingly reddish and a crimson red tail. In most cases fresh water fish are smaller tan marine fish with only a few attaining giant size. The arapaima is one of the larger ones said to reach nearly 15 feet in length and 440 pounds in weight.
The family to which the arapaima belongs is characterized by stout, bony scales that each contain canals forming a mosaic-like pattern. The age of this fish is indicated by rings inside the scales. This fish matures in 4 to 5 years and is only known to live around 18 years. It is placed in the Osteoglossidae family with a lineage that can be traced back over 100 million years. In some ways this makes the arapaima a living fossil with some of it's more primitive features including the bony head, peculiar shaped fins, lobe like tail and lung which is air bladder like.
The arapaima is essentially a fish eater but appears to be ready to eat almost anything. It preys upon the hassar, lukamani and baira, but examination has revealed the remains of may other items including water snails, fresh water shrimp, worms, vegetable matter, fresh water turtles, snakes, frogs, crabs, grasshoppers, pebbles, sand mud and even coal. Breeding season for the arapaima last from December to May with spawning taking place in shallow water. During April and May when the rivers over flow to flood the low lands the arapaima move into shallow water to select sandy areas that are clear of vegetation to hollow out their nest. The nest are up to 20 inches across and around 8 inches in depth. During the breeding season the female turns a chestnut shade while the male develops a black head and bright vermilion tail.
The female lays up to 180,000 eggs in several different batches and with each batch in a separate nest. Eggs are between 1\8 to 1\4 inch in diameter and the hatch within five days of being laid. The tiny hatchlings are long and black, swarming near the males head so that as he rises to the surface to gulp air they are made invisible. They will also use this camouflage when they are disturbed while the females swims around the father and off spring ready to drive any intruders away. The arapaima is preyed on by man, being caught and eaten in large numbers. The jaguar is also said to catch and eat this fish.
In most cases the arapaima keeps to shallow waters where it swims about lethargically, occasionally rising to the surface to gulp air into its swim bladder which opens by a duct in the back of the fishes throat. The swim bladder on this fish is large, occupying the entire area above the gut. It is made of a cellular, lung like tissue and opens directly into the gullet. While the linage and anatomy of the arapaima are in little doubt, the size of this fish has been the subject of much speculation. Although every book that talks about the arapaima states a tremendous length and weight it is believed that these figures are a myth. With the great numbers of these fish caught every year the largest one catalogued was 7 feet long and weighed only 246 pounds.