Incubation Environment and Hatching Management Technology of cultivated Monopterus Albus

The hatching rate of fertilized eggs of Monopterus Albus is affected by many environmental factors, including water temperature, dissolved oxygen and enemy organisms.

The main results are as follows: (1) the embryonic development of Monopterus Albus is closely related to the water temperature. It is mainly manifested in three aspects: first, embryonic development must be carried out at a suitable water temperature, too high and too low will lead to a decrease in hatchability or embryo deformity. The results show that the suitable water temperature for the embryonic development of Monopterus Albus is 21: 28 ℃, and the optimum water temperature is 24: 26 ℃. Second, in the suitable range of water temperature difference, too large or too fast water temperature difference will also cause embryo deformity or death, and it is usually required that the temperature difference within a short period of time should not exceed 3 ℃, preferably no more than 1 ℃. Third, the embryonic development time of Monopterus Albus is directly affected by the water temperature. When the water temperature is about 30 ℃ (28 ~ 36 ℃), the embryonic development takes 5 ~ 7 days, and when the water temperature is about 25 ℃, the embryonic development takes 9 / 11 days.

(2) the embryos of Monopterus Albus can not make use of oxygen in the air, but can only absorb dissolved oxygen in water by vascular osmosis. Too low dissolved oxygen in water will cause growth retardation, stagnation, and even suffocation. The results showed that the oxygen consumption of 100 Monopterus Albus eggs per hour at 24 ℃ water temperature was 0.29mg in cell division stage, 0.46mg in blastocyst stage and 0.53mg in gastrula stage, which was much higher than that of embryonic development of "four big domestic fish". Therefore, in the process of hatching, the oxygen content of hatching water should be close to or reach the saturation of dissolved oxygen in water.

(3) fresh water quality plays an important role in improving the hatching rate. Pesticide or industrial polluted water should never be used as hatching water. It is best to build a reservoir or arrange a special pool to provide hatching water, and filter before citation to prevent the entry of enemy organisms and dirt, affecting the improvement of hatching rate. The pH of water should be neutral.

(4) under the condition of artificial reproduction, larger enemy organisms are easy to be eliminated (such as tadpoles, small fish, shrimp, etc.), but smaller cyclops are easy to be ignored. in fact, Cyclops pose a great threat to eel eggs and larvae, they can pierce the egg membrane or bite eel seedlings with appendages, and then suck eel eggs and eel seedlings as nutrition, and the injured eel eggs or eel seedlings die quickly. The best way to prevent Cyclops is to filter the water used for hatching and install the filter at the inlet.