What is this saltwater fish that has a strange appearance, a difficult name to write, and is difficult to tell male from female?

The brindle fish, commonly known as "butterfly fish", "flower fish" and "young lady fish", belongs to the order Perciformes, family Brenidae and genus Brendle. It is distributed in the Yellow Sea of ​​Liaoning, the southern part of Liaodong Bay and the Bohai Sea. It is mainly found in North Korea and Japan. It has a narrow and flat body, with orange, orange-red and light brown body colors. There are horizontal stripes or stripes on the dorsal fin, anal fin, pectoral fin, caudal fin and body sides. The head and the front spines of the dorsal fin have developed rib-shaped cortical protrusions. They are benthic omnivorous fish with wide round pectoral fins, as well as long dorsal and anal fins. These physiological characteristics can help them sprint short distances and quickly catch food.

The pliers are dioecious fish. They can reach sexual maturity at the age of 2, and there is no significant difference in the size of adult fish. The male and female can be distinguished by the appearance of mature pliers (as shown in the picture). The male fish has a larger pliers-like cortical protrusion on the front fin spine of the dorsal fin, which is darker brown-black in color; while the protrusion at the front end of the dorsal fin of the female fish is smaller, brown-black at the bottom, and lighter in color at the top, which is light orange.

Research data shows that mullets only lay eggs once a year, and their gonad development changes throughout the year. An adult female fish weighing one kilogram carries an average of 22,500 eggs, which is a relatively large number of eggs among fish. The gonads of mullets near the Lushun area of ​​Dalian City develop to their most mature state in October, but the gonads of male fish mature earlier than those of females in September. Research on the biochemical composition of mullets liver and muscle has shown that the nutrients after the breeding period are less than those before the breeding period, indicating that the breeding behavior consumes the nutrition of the fish body. This research result can also scientifically guide us on how to choose nutritious edible fish.

There is also a scientific method to know the age of the plioped bream: biologists generally believe that the various parts of the fish body grow in synergy. Based on this principle, the periodic activities of fish will leave growth marks on various calcified tissues (vertebrae, otoliths, scales, fin rays, etc.), forming annual rings, which is the age of the fish. Scales are usually selected as the identification material for the age of fish. The ring patterns on them can be used as a basis for explaining the age increase of fish. In addition, bone materials such as otoliths, opercula, fin rays and vertebrae can also be used for age identification. Because the scales of plioped bream are small, they are difficult to collect and observe; otoliths are fragile and difficult to polish, and the fitting degree of the fitting equation between the weight of otoliths and body length and weight is low, and other bone materials cannot be clearly identified. Therefore, vertebrae are selected as the material for the identification of the age of plioped bream. Studies have found that the best material for the identification of the age of plioped bream is its 6th to 10th vertebrae. After simple treatment, clear ring patterns can be clearly observed under a general optical microscope.

The growth rate of fish is not constant. Through the investigation of the catch of fishing boats, it was found that individuals aged 1-8 years old appeared. The body length of the catch of mullet ranged from 11.49 to 35.83 cm, of which individuals of 13 to 27 cm accounted for the majority, accounting for 89.41% of the catch. The weight range was 16.29 to 592.00 g, of which individuals under 200 g accounted for 86.47% of the catch. The dominant age range was 2 to 4 years old, accounting for 78% of the total catch. By studying the relationship between age and weight, a mathematical model was used to infer that 7.77 years old is the turning point of the growth of mullet. After this time point, the growth rate slowed down significantly. This is the professional term "growth inflection point" in fish biology. 2 to 4 years old mullet is in the period of sexual maturity and reproduction. If a large number of fish are caught at this time, the group's reproductive capacity will be reduced, which is not conducive to the population reproduction and resource protection of mullet.

As a member of marine life, the mullet deserves our deeper understanding and research so as to protect the ocean and biodiversity.

References:

[1]. Chen Bing. Age and growth of mullet in the Yellow Sea, Dalian[J]. Hebei Fisheries, 2017.9.

[2]. Chen Bing. Reproductive biological characteristics of mullet[J]. Fisheries Science, 2018.7.

[3]. Chen Fei. Study on the biological characteristics of Azuma emmnion[J]. 2017.