Generally speaking, male arowana is longer than female arowana under the same conditions. It seems that males of most biological species are bigger than females.
Feature 2: the shape of the ventral fin of arowana
Usually, the ventral fin of male arowana is pointed and long, while the ventral fin of female arowana is not very long, not as long as that of male arowana.
Feature 3: the abdominal type of arowana.
In the mature individuals of arowana, the abdomen of female arowana is obviously raised because of its eggs, which is also the characteristic that directly distinguishes the males and females of arowana.
Feature 4: The head size of arowana.
Because the male arowana needs to contain eggs in its mouth, the male arowana has a larger head shape.
Feature 5: the shape of the gills of arowana.
The female arowana can see a beautiful A on her cheeks, and the arrow part is shorter than that of the male arowana. The a of male arowana is irregular and the arrow part is long.
These are the five obvious characteristics of how arowana distinguishes between males and females, but even so, it is still difficult to distinguish them without a good reference.
Extended data:
Double-bearded bone tongue fish (scientific name: Osteoglossum? Bicirrhosum), also known as arowana, is distributed in the Amazon River basin. It is an important local catch and one of the main ornamental fish, and it is also quite popular in Asia because of the demand of geomantic omen.
Arowana is long and flat, with a fan-shaped tail, and its dorsal fin and anal fin are strip-shaped and extend backward to the base of the tail stalk.
The lower jaw is more prominent than the upper jaw and has a pair of short and thick beards.
Five rows of large scales are neatly arranged on the broad fish of arowana, shining silver in the light. Each fin reflects a bright red or orange luster under the light. The body color of young fish is blue; Both dorsal fin and anal fin have red and blue edges. The scales of Jinlong are golden, and all the fins are golden red.
The body color of the red dragon is golden yellow, the scales are golden red, there are dark red spots on the mouth and gill cover, and all the fins are dark red. The body of the silver dragon is silvery white, the body of the black dragon is silvery white and purplish blue, and all the fins are blue black. Arowana can reach 50~ 100 cm in length.
The silver belt has a very slender body shape. The position of the mouth is above, and the fissure extends to the posterior edge of the orbit. The lower jaw protrudes from the upper jaw, and several linear lateral devices are arranged side by side in front. There are a pair of tentacles on the snout. The tentacles of adult fish can grow to 3-4cm in wild individuals swimming in the natural environment, but only to 1-2cm in artificially raised individuals.
The odontoid bone of the mandible is well developed, and the conical teeth arranged like a comb between the upper and lower jaws are very small and sharp, and the tooth spacing is very narrow. Not only the front of the maxilla, but also the butterfly bone and hyoid bone attached to the dentate joint are well developed, for biting large crustaceans and beetles? From the arowana exhibition.
In addition, compared with the bite force of teeth, the upper and lower jaws pay more attention to the hunting function of easily catching prey. The gill harrow develops into a thorn. Gollum's big eyes are close to the front of the palate, and his vision is very good. The kiss is short. The nostrils are located in the front and upper parts of the eyes, very close to the nose and mouth. Both dorsal fin and gluteal fin are very long, and the starting point of gluteal fin is more forward than dorsal fin.
The first spine of the stretched ventral fin even exceeds the starting point of the gluteal fin. The pectoral fins are well developed. In particular, the long and powerful first thorn is a sharp weapon for the silver belt to jump out of the water. This wonderful flying power makes the silver belt win the "jumping fish" in South America (Amazon "water monkey"), which is easy to jump at night, so more protective nets are added. ) laudatory name.
The side of arowana is covered with five rows of big and beautiful round scales. The lateral line extends from the top of the posterior margin of the branchial lid behind the head to the caudal stalk. The body height is about one fifth of the body length. The male fish between five and eight years old, about 90cm, is much taller than the female fish.
The middle part of arowana's body can even be close to two centimeters. This attractive appearance is not comparable to the expensive Asian arowana. It's a pity that this kind of silver belt is hard to find.
References:
Baidu encyclopedia-arowana