The selection of broodstock will determine the final result of hatchery activities. This is because good seeds are obtained from good breeders. The purpose of selecting broodstock is to obtain good quality broodstock (Sari, 2021). This activity is carried out after gonad maturation and before spawning. Pangasius broodstock is superior if the eggs produced are in optimal conditions, both in terms of quantity and quality. So far, many fish cultivators have spawned without regard to the broodstock used, so there will be a risk of inbreeding and the impact on the poor quality of the seeds due to a decrease in the recessive nature of the parent fish. This of course will make seed growth slow and susceptible to disease.
In general, the characteristics of a good Pangasius broodstock fish are fast-growing, aggressive, free from defects, and healthy (Sari, 2021). In addition, the age and size of the Pangasius broodstock must be different to better ensure the offspring of the broodstock in hatchery activities, so it is better to choose a superior broodstock. This will have a positive impact on cultivators to reduce production costs, especially feed costs. The shape and size of the gonads are influenced by several factors, including the individual body shape of the fish, the shape of the abdominal cavity, the size of the fish's body, the feed given during gonad maturation, and physiological factors of the fish's body.
Below are the characteristics of broodstock Pangasius that have matured gonads and are ready to be spawned, including the following:
1. Female broodstock
Generally, female broodfish that have matured gonads have easily identifiable characteristics. The posture of the female broodfish tends to be wide and short, the belly is soft, smooth, and enlarged towards the anus. Urogenital swelling and opening and dark red (Sunarma, 2007). The characteristics in detail are as follows:
- More than 2.5 years old.
- The minimum weight of female broodstock is 3 kg/head.
- The abdomen is enlarged towards the anus.
- The stomach feels soft and smooth when touched.
- The genitals are swollen and dark red.
- The skin of the Pangasius on the belly is soft and thin.
- When pressed, an egg that is round in size will come out with a uniform size.
- Eggs were taken using a catheter and visually observed the level of maturity in the sera solution. The fish selected for spawning are those with eggs with a diameter of 1-1.2 mm, uniform, opaque color, and a core position in the middle.
2. Male broodstock
Generally, mature male broodfish gonads can be seen from their relatively slender and long body posture. The genitals (urogenital) are swollen and dark red. If the abdomen near the genital opening is massaged, it will release a thick white liquid (sperm fluid) (Sunarma, 2007). The characteristics in detail are as follows:
- More than 1.5 years old.
- The minimum weight of male broodstock is 2 kg/head.
- The skin of the Pangasius on the belly is soft and thin.
- When around the abdomen is pressed will come out white sperm fluid.
- The genitals are swollen and pink in color.
Source: @DJPB_SEIGELAM
Gonad Maturity Level (GML) and Gonad Maturity Index (GMI) in Pangasius broodstock
GML (gonadal maturity level) is the stage of the gonadal condition, starting from the beginning of gonadal development to the final stage before or after spawning occurs(Effendie, 1979) while the Gonad Maturity IndexGMI (gonad maturity index) is an index value that can determine the condition of the gonads. Determination of gonadal maturity level and gonadal maturity index in Pangasius broodstock is very important to do.
The level of gonad maturity can be known by observing the characteristics of the female Siamese Pangasius broodstock sexual organs using the cannulation method (Effendi, 1997). This method is widely used for fish with large gonad sizes such as Pangasius. The reason is, this method is easy, fast, and practical to do. The complete gonad maturity level is as follows.
Table 1. GML and GMI in Pangasius
|
Stage |
Female broodstock |
Male broodstock |
|
I |
Ovaries are like threads, long to the front of the body, clear color, and smooth surface |
The testes are like threads, shorter, the ends are in the body cavity, and the color is clear |
|
II |
Larger size, dark yellowish coloring, eggs are not clearly visible |
The size of the testes is larger, the coloration is milky white, and the shape is clearer than in stage one (1) |
|
III |
Ovaries are yellow, morphologically the eggs are visible with the eyes |
The surface of the testes looks jagged, and the color is getting whiter, in a preserved state it is easy to break |
|
IV |
The ovaries are getting bigger, the eggs are yellow and easy to separate, the oil grains are not visible, fill 1/2-2/3 of the body cavity, and the intestines are pushed into the body cavity |
As with Stage III, the testes become denser, and the body cavity begins to fill up, the color is milky white |
|
V |
Ovaries are wrinkled, with thick walls, and residual eggs are near the release |
The testes on the back are deflated and the part near the release is still filled |
References:
Effendie, M I. 1997. Biologi Perikanan. Yayasan Pustaka Nusatama. Yogyakarta
Effendie, M. I. 1979. Metoda Biologi Perikanan. Cetakan Pertama. Yayasan Dewi Sri. Bogor
Sari, L. A., 2021. Penggunaan Teknik Pemeliharaan Induk Berkualitas Tinggi pada Ikan Patin Siam (Pangasius hypophthalmus). [Online]
Available at: http://news.unair.ac.id/2021/05/18/penggunaan-teknik-pemeliharaan-induk-berkualitas-tinggi-pada-ikan-patin-siam-pangasius-hypophthalmus/
[Diakses 23 Mei 2022].
Sunarma, A., 2007. Panduan Singkat Teknik Pembenihan Ikan Patin (Pangasius hypophthalmus). 1st penyunt. Sukabumi: BBPBAT Sukabumi.
