IMNV or Infectious Myonecrosis Virus, which is also often referred to as Myo, is one of the most vicious and deadly diseases in shrimp. This one disease can cause great losses to Vannamei Shrimp Farmers if it is not prevented or handled properly.
Before taking steps to prevent or treat it, it is better for you to get to know the characteristics of this disease that originated in Brazil.
Myo disease in vannamei shrimp, or also known as IMNV, is caused by a virus with the same name as the disease, namely Infectious Myonecrosis Virus (IMV). This one virus attacks and destroys striated muscle tissue in shrimp. This disease that attacks vannamei shrimp cultivation can only be observed in shrimp that are 40-60 days old. This disease in shrimp can cause death in shrimp within 9-13 days after the shrimp are infected.
There are two ways IMNV or Myo can be transmitted, one of which is vertically. The virus can be transmitted vertically from brood to fry. That is why it is very important for you to choose fry that are healthy and not infected with IMNV.
Apart from being vertical, Myo can also be transmitted horizontally, through cannibalism or water. Decreasing water quality, especially due to temperature fluctuations, will trigger the growth of Myo. Leftover food that accumulates at the bottom of the pond will turn into toxic ammonia, causing stress, death, or disease for the shrimp.
Characteristics of Myo Disease in Shrimp
After getting to know Myo disease, let's check the characteristics of Myo disease in shrimp!
1. The color of the shrimp becomes pale
Shrimp infected with IMNV will turn pale in color and lose their transparency.
2. White Color Appears in the Muscles
Shrimp muscle turns white like cotton. In addition, you will see white lumps on the body segments of the shrimp that are infected with IMNV.
3. Abdomen to Reddish Tail
One of the most visible signs of IMNV is the appearance of pink or dead tissue on the tail. The color is similar to boiled shrimp.
4. Cramps in Muscle Tissue
Shrimp muscle tissue is a tissue that is attacked by the Myo virus. One of the effects is that the muscle tissue will cramp and the movement of the shrimp will be disrupted.
5. Hepatopancreas Size Shrinks
The hepatopancreas, or the part of the shrimp's stomach near the head, will shrink due to infection with this virus.
How to Overcome Myo Disease
Myo disease is very easy to treat when it is still in the early stages of infection, when the shrimp are just starting to turn pale and redden from the lower vertebrae to the belly.
Here's how to deal with myo disease in vannamei shrimp!
- Maintaining the stability of water quality, especially temperature, salinity and pH.
- Increase aeration.
- Provide additional feed containing vitamin C.
- Give molasses (25% of FR/day)/probiotics.
- Reducing/stopping feed temporarily.
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To date, there is no effective vaccination against IMNV. However, this disease in shrimp can be prevented with strict biosecurity. One of the steps that you can take is to choose fry that have been proven free from disease or SPF (Specific Pathogen Free). Usually, fry that are good and disease free have a checking certificate.
Want to know more about Myo disease and how to treat it? Let's check the video Learn Cultivation in app eFarm!