1. Classification
– Pangasius is one of the species of Pangasius (Pagasiidae) found in the lower Mekong River (Cuu Long) in Vietnam.
– According to the classification system, Pangasius is classified as follows:
– Catfish (Siluormes) s)
– Pangasius family (Pangasiidae)
2. Distribution
– Pangasius is distributed in Mekong river basin, present in all 4 countries of Laos, Vietnam, Cambodia and Thailand. In Thailand they are also found in the Mekong and Chao phraya basins. In our country fry and fingerlings are mainly found on the Tien River, mature fish found only in ponds, rarely found in the wild.
3. Morphological and ecological characteristics
– The body is long, without scales, black and gray on back, slightly silvery belly, wide mouth, has 2 long beard tails.
– Fish live mainly in fresh water, can live in slightly brackish water (10-14% salinity), can tolerate alum water with pH> = 4 (pH below 4, the fish refuses to eat, is shocked ), low tolerance to temperatures below 150C, hot to 390C.
4. Nutrition characteristics
– Completed oysters prefer to eat fresh bait, so they eat each other right in the hatchery, even fish caught in the river still see them eating each other in the bottom of the fish fry. They feed on animals that are about the size of their mouth.
– When the fish is big, omnivores are biased towards animals and easily switch food types. In Pangasius farming ponds, it is able to adapt to a variety of foods, including compulsory foods such as humus, organic residues, bran, vegetables, compost, benthos, ….
5. Growth characteristics
– Fish in the wild, can live over 20 years. Met a wild fish size of 18 kg or a sample up to 1.8m long. In the rearing pond, the parents give birth to 25 kg in 10-year-old fish.
– Pond rearing 1 year fish reach 1 – 1.5 kg / head (the first year), in later years the fish grow faster, sometimes reach 5-6 kg / year.
6. Reproduction characteristics
– Maturity: Male catfish matures at age 2 and females at age 3 and above.
– Pangasius has no secondary (secondary) genital organs, so it is difficult to distinguish male – female appearance from external appearance.
– In the maturation period, the gonads in males grow large called ovaries, in females called ovaries.
– The mature season of fish in the wild starts from May to June (solar calendar), the fish spawn naturally in the river in the river sections with suitable ecological conditions. Fish do not spawn in the river section of Vietnam. In Cambodia, the spawning grounds for the fish are located at the intersection of the Mekong and Tonlesap rivers, from Sombor, Crache Province and above.
– In artificial reproduction, we can breed early maturity and give birth earlier in the wild (March).
– In nature, there is no recurrence. Only in artificial conditions, Pangasius can recur 1-2 times a year.
– The number of eggs counted in the ovaries of our fish is called absolute fertility. The absolute reproduction of Pangasius can range from 200,000 to several million eggs.
