How to properly and reasonably fertilize fish ponds in aquaculture

Conventional fertilizing methods have certain advantages and disadvantages. How to fertilize, how to fertilize correctly, let's discuss with you the fertilizing before fry release and the pros and cons of conventional fertilizing

I. How to fertilize before fry release

1. The nutrients in the fertilizer used for fertilizing (nitrogen, phosphorus, potassium and other trace elements) should be comprehensive and mutually balanced.

2. Inorganic fertilizer (chemical fertilizer) is a fast-acting product; although it fertilizes the water quickly, its duration is relatively short;

Organic fertilizer is a long-acting product; although it fertilizes the water slowly, its duration is relatively long. Reasonably combining the two can achieve a good fertilizing effect that is both fast and stable.

3. When using inorganic fertilizer, apply it in small amounts multiple times according to light conditions. Apply more when the weather is sunny and the light duration is long, and apply less but more frequently otherwise. Be sure to note that after fertilizing on cloudy and rainy days, a large amount of fertilizer sinks to the bottom of the pond, which may cause "moss" to multiply in large quantities, failing to fertilize the water and instead having the opposite effect.

4. The amount of base fertilizer in the fish pond should be sufficient. The existing nutrients in the pond (such as silt, trace elements, etc.) as well as the nutritional structure and quantity of the base fertilizer applied must be taken into account. Apply less when there is a lot of bottom mud, and apply appropriately more when there is little bottom mud or in new ponds.

5. When there is relatively little bottom mud in the pond, applying microbial preparations alone (aquaculture EM bacteria probiotics) has a poor fertilizing effect, because after these bacteria are applied, there are no nutrients available for them to decompose into fertilizer.

6. After fry release, supplementary fertilizing should be applied in small amounts multiple times. Use less urea and other nitrogen fertilizers, and use them with caution; otherwise, ammonia nitrogen content may increase. Use as many microbial probiotics as possible to promote the massive reproduction of beneficial bacteria in the fish pond, so as to decompose pond silt and dead animal bodies as nutrients.

7. When the actual nitrogen-to-phosphorus ratio in the water body exceeds 10:1, diatoms tend to multiply in large quantities; when the nitrogen-to-phosphorus ratio is 3:1-7:1, or even close to 10:1, green algae tend to multiply in large quantities; but when the nitrogen-to-phosphorus ratio is close to 1:1, toxic dinoflagellates and flagellates tend to reproduce.

8. After fertilizing, the water transparency should be around 30cm. Green water (light green, emerald green, yellow-green or mung bean green) is relatively more stable than brown water (tea-colored, tea-brown). To cultivate relatively stable water, try to adjust the variety and quantity of fertilizer applied to cultivate green water.

II. Advantages and disadvantages of conventional fertilizing methods

The conventional practice of general fertilizing is to first clear the pond, disinfect the pond, then fill with water, disinfect and fertilize. The water can basically be fertilized, but in many cases, within a week or at most about half a month, the water becomes clear or the algae collapse or the algae species shift. If only products containing chemical fertilizers are used for fertilizing, the effect is relatively quick, but the duration is not long. Perhaps quite a few farmers use chicken manure, duck manure, pig manure, wheat middlings (commonly known as "yellow powder"), peanut bran, soybean meal, rice bran plus some chemical fertilizers, commercially available fertilizing products and other methods to fertilize, and the fertilizing effect is quite good, but often after about ten days to half a month, the water easily becomes clear, the algae collapse or the algae species shift. That is because the nutrients applied are still not comprehensive and balanced, leading to a deficiency of certain nutrients (mostly sufficient nitrogen fertilizer but insufficient phosphorus fertilizer), so the growth of certain types of algae is inhibited, while it happens to be suitable for the growth of another species of algae, causing an algae species shift. Some people also use live bacteria products to fertilize, such as photosynthetic bacteria, Bacillus, nitrifying bacteria, etc. Some show effects, and some do not show obvious effects. Why? Live bacteria mainly play a decomposing role, and they decompose gradually. If the nutrients applied are not much or the silt is not much, the fertility is certainly insufficient. If the fertility is insufficient, the water will inevitably change. Especially in new ponds, where feeding is low in the early stage of aquaculture and shrimp excrement is very little, the nutrients in the pond water are few, so how could the effect of applying bacteria last too long? Unless some substances with comprehensive nutrition are added to ordinary live bacteria products.

Usage and dosage of aquaculture EM bacteria:

Apply directly into water to regulate water quality, degrade nitrite, reduce ammonia nitrogen content, lower pH, ferment organic fertilizer, improve pond bottom, increase dissolved oxygen, sterilize and disinfect, etc.

Taking 10 mu of water surface as an example: dilute 10 kg of aquaculture bacterial liquid with 50 times water, then evenly splash it on the water surface. It can also be evenly mixed with bait in the above proportion when feeding and then released together. The use cycle is generally 2-3 times per month. Generally, it is applied on sunny mornings.

Benefits after using aquaculture EM bacteria to improve water quality:

1. Reduce pathogenic microorganisms and harmful algae; significantly enhance the immunity and disease resistance of cultured organisms (such as fish, shrimp, crabs, sea cucumbers, frogs, shellfish), reduce the incidence rate, and increase the survival rate of seedlings.

2. Increase zooplankton and beneficial algae on the water surface, especially the continuous increase of red worms.

3. Stabilize and improve water quality, promote the decomposition of residual bait and other floating organic matter, degrade harmful substances such as ammonia nitrogen, nitrite, and hydrogen sulfide, increase dissolved oxygen in water, and promote the growth of beneficial plankton in the water body.

4. Fish and shrimp feces, pond bottom impurities, and scraps will not become silt but appear in a loose, sand-like form.

5. Promote growth, shorten the growth cycle, and significantly increase the weight gain rate. Under the same environment, after using aquaculture EM stock solution, market listing can be advanced by 10-15 days, the average yield per mu can be increased by 20%-35%, the egg production can be increased by 25%, the spawning time is prolonged, and the hatching rate is relatively good; the bait does not stink, improving the aquaculture environment.

6. Adjust the aquaculture ecological environment, increase dissolved oxygen in water, promote the activation and growth of normal flora and beneficial algae in the aquaculture system, and maintain the ecological balance of the aquaculture water body.

Aquaculture EM bacteria can not only fertilize fish and shrimp ponds, but also degrade the nitrite content in fish and shrimp ponds