Shrimp are low level animals, do not have a specific immune system, so their resistance to pathogens is poor. Therefore, when growing in captivity, shrimp are very susceptible to diseases from many different agents such as viruses, bacteria, fungi, toxic algae…
Shrimp are low level animals, do not have a specific immune system, so their resistance to pathogens is poor
Unlike in the natural environment, cultured shrimp grown in the artificial stocking environment are very sensitive to pathogens. Because no matter how well it is handled, the pond is essentially a closed environment with waste from shrimp feces, rotting leftovers, decomposing peeled shrimp shells, etc., gradually accumulating during the farming process. This creates the ideal conditions for pathogens to develop, making it easier for shrimp to get disease once they are shocked or have reduced resistance. The following are some of the most common pathogens:
1. Virus
Viruses, also known as super bacteria, are microscopic parasites that cannot reproduce and make their own proteins, so they are completely dependent on their host. In farmed shrimp, it can be said that viruses are the main pathogens with common dangerous diseases such as White Spot Syndrome Virus (WSSV), Infectious Myonecrosis Virus (IMNV), Taura Syndrome Virus (TSV) …
Virus disease has the ability to spread quickly and widely, and in the acute stage can easily cause mass mortality of shrimp. Currently, there is no preventive vaccine as well as specific medicine for virus diseases, so it is still mainly to prevent diseases by thoroughly cleaning and disinfecting ponds and doing good selection of varieties.
2. Bacteria
Bacteria are a group of single-celled organisms that are small and usually have a simple cell structure without a nucleus. Bacteria are agents that are frequently present in ponds, which are both beneficial such as Lactobacillus, Bacillus spp., Nitrosomonas… and harmful and pathogenic for shrimp, especially Vibrio spp.
In shrimp, there are common bacterial diseases such as luminous disease, acute necrosis, black spot disease, white feces disease… To prevent diseases, it is necessary to manage the pond environment carefully and use probiotic products such as TA-Pondpro to promote the growth of beneficial probiotics in ponds. In addition, it is also possible to use T-Food, a probiotic product using fermented Lactobacillus spp, to improve the intestinal biota of shrimp, both to help limit the growth of harmful bacteria and to strengthen the ability to digest food for shrimp to grow quickly.
For severe infections, antibiotics can be used, but be very careful about the dose and duration of use.
3. Protozoa
Protozoa are a simple life form, although the body has only one cell, it is capable of carrying out a full range of life activities as a complete multicellular organism. Poorly cared ponds, excess food, and high organic content will create ideal conditions for protozoa to proliferate, especially strains of Zoothamnium, Epistylis, Vorticella… They will compete for dissolved oxygen. At the same time, it attaches to the shrimp body (along with algae, fungi and other species) causing coagulation disease, black gill disease which, if not treated promptly, will cause shrimp to weaken, molt abnormally and may be superinfected with other pathogens factors.
In addition, these protozoa also cling to the pond bottom, creating a viscous layer on the surface, accumulating waste and becoming the residence of many harmful bacteria. This slime is also the favorite food of shrimp, thereby indirectly causing liver and intestinal diseases. Therefore, it is necessary to periodically treat the pond bottom and water with probiotic products to stabilize the quality of the culture environment. In parallel with maintaining a high dissolved oxygen content, it is necessary to carefully manage the shrimp’s diet, ensuring adequate nutrition but also avoiding excess.
4. Environment
The environment, specifically water quality, is one of the major factors affecting the health and development of shrimp. There are many factors that determine the quality of the environment such as temperature, dissolved oxygen, pH, alkalinity… and also heavy metals, and changes in these factors will indirectly or directly cause disease. for shrimp.
For example, the environment with low pH conditions and many heavy metal ions such as Fe3+, Al3+ will cause black gill disease on shrimp (due to salted heavy metal ions); Or the environment accumulates a lot of organic substances, causing the concentration of toxic gasses NH3, H2S to increase, combined with factors with low dissolved oxygen content and high pH can cause swelling of gills and yellow gills.
To limit pathogens from the environment, the best way is to implement environmental management measures well. Along with regularly checking, monitoring and quickly handling when problems occur.
Besides the factors mentioned above, shrimp can also get sick by many other factors such as fungi, algae, weather… In addition, the resistance of shrimp is also a decisive factor because when shrimp have weak resistance or frequent shock it will easily be penetrated by pathogens.
5. Prevention is better than cure
For farmers, the occurrence of disease in the herd is a risk that no one wants to happen. Because once shrimp are sick, with a high density stocking environment and scavenging habits, the disease will quickly spread to the whole shrimp population. The treatment of the disease, no specific medicine or expensive, is effective because the diseased shrimp often stop eating, causing the medicine mixed in the feed not to get into the shrimp’s body.
Prevention is better than cure
Therefore, in shrimp farming, disease prevention is still the key factor determining the success or failure of the crop. It is necessary to do well in disease prevention right from the breed selection, pond improvement and water treatment, while maintaining favorable environmental factors for shrimp growth by:
- Improve venturis to provide oxygen, create favorable conditions for probiotic to decompose waste and release toxic gasses;
- Cut excess feed to reduce waste pressure polluting the pond environment;
- Limit water change, and only replace it with treated water through settling ponds;
- Periodically every 7-10 days, use TA-Gold probiotic products to decompose detritus, and at the same time add probiotic to help a favorable pond environment for shrimp to grow;
- Improve the resistance of shrimp with vitamins and minerals.
It is necessary to closely monitor the health status as well as the water environmental parameters to have treatment intime. In case of detecting diseased shrimp, it is necessary to identify the pathogens early by accurate testing methods such as histopathology, PCR and conduct the right treatment with the right drug, right dose, right time.
