CATDOLL : CATDOLL: Are catfish and silver carp the same fish? What’s the difference?

Catfish belong to the order Siluriformes, and are related to characins, carps, and some small carp of the Cyprinidae family. Some ichthyologists believe that they can be classified as the same order Osteognathiformes; some ichthyologists believe that they should belong to different suborders under the order Osteognathiformes, with catfish belonging to the suborder Siluriformes and characins, carps, and small carp of the Cyprinidae family belonging to the suborder Cyprinidae.

Catfish are characterized by whisker-like tentacles on their mouths. At least one pair is above the upper jaw, and some have another pair on the mouth and another pair on the lower jaw. Many catfish have spines on their backs and pectoral fins. They may have poison glands on their spines, which can cause pain and damage when stung. All catfish have no scales, and their skin is either naked or covered with bony shields.

There are about 2,500 species of catfish in existence, belonging to 30 families. Most live in freshwater, while catfish belonging to the marine catfish family and the eel catfish family live in the sea. Freshwater catfish are widely distributed in various freshwater areas around the world. They can be found in fast-flowing rivers that flow through mountains to slowly flowing or even stagnant lakes. Saltwater catfish live near the coasts of tropical areas. Catfish like to swim underwater and are more active at night than during the day. Most of them eat all kinds of animals and plants. Both male and female catfish have the obligation to raise their offspring. For example, the brown bighead catfish will dig holes to raise and protect their children. Male marine catfish will hold marble-sized eggs and newly hatched fish in their mouths, and they are extremely precious.

There are big differences in length and weight among catfish. The smallest catfish is only 4-5 cm long, while a large European catfish can reach 4.5 meters long and weigh up to 300 kg. The difference is obvious. Many people like to raise smaller catfish. Many larger catfish can be eaten, and are the target of people's fishing and dishes on the table. For example, the blue catfish can be up to 1.5 meters long and weigh up to 68 kg; the freshwater catfish can be up to 1 meter long and weigh up to 12 kg; they are all one of the main edible fish for residents in the Mississippi River Basin and the Gulf of Mexico in the United States.

Although there are many species of catfish and they are widely distributed, there are also several species such as the giant catfish and the Mexican Yaqui River catfish that are rare and endangered.

Silver carp (Hypophthalmichthysmolitrix) is also called silver carp or silver carp. It has a flat body, a bluish-grey back, white sides and belly. It has a relatively large head. Its eyes are located very low. Its scales are small. The horny ridge in the middle of its abdomen extends from the bottom of the pectoral fins to the anus. The pectoral fins do not exceed the base of the pelvic fins. The fins are greyish white. Silver carp is impatient and good at jumping. It lives in the middle and upper layers of the water. (Figure 1-6)

Silver carp is a typical filter-feeding fish. It mainly feeds on zooplankton in the fry stage. When it grows to more than 1.5 cm, it gradually turns to phytoplankton. It also eats soy milk, soybean dregs powder, bran and rice bran, and prefers artificial micro-particle compound feed. It is suitable for breeding in fertile water. The length of the intestine is about 6-10 times the body length.

Silver carp reaches sexual maturity 1-2 years earlier than grass carp. Mature individuals are also smaller, and female fish over 3 kg can generally reach maturity. Female fish weighing about 5 kg can carry about 40,000 to 50,000 eggs per kg of body weight, and an absolute egg carrying capacity of 200,000 to 250,000 eggs. The eggs are buoyant. The spawning period is the same as that of grass carp. In recent years, it has been found that silver carp farmed in the mainland have degenerated, mainly because of their small size and early maturity. Therefore, attention should be paid to introducing seedlings from the place of origin to purify and rejuvenate.

Silver carp is also a large fish, which can weigh up to 30-40 kg in natural rivers. Under pond conditions, if there is sufficient bait, a one-year-old fish can reach around 0.8 kg. The weight of commercial silver carp suitable for market is preferably 1.5-2 kg.