Shrimp Diseases (Prawn), Symptoms, Treatments

Shrimp Diseases, Symptoms, Prevention and Treatment:

Today, let us discuss about Shrimp Diseases (Prawn).

Introduction: Prawns /Shrimp suffer from various diseases that are infectious and non-infectious. Infectious diseases are infected due to viruses, bacteria, fungi and other parasites. Treatment is not properly if the diseases occur in the  pond. The best way to get rid of diseases is by implementing good farm management or prevention. Below are some diseases that occur in prawn farming.

Infectious Diseases In Prawns / Shrimp:

Viral Diseases in Prawns /Shrimp:

Monodon Baculovirus Disease (MBV):

Symptoms: the major symptoms are Lethargy, anorexia, loss of appetite, dark coloration and low growth rate. Infected prawns may suffer with fouling of the gills and appendages by ciliates such as Zoothamnium spp. and Vorticella spp. Severe infection leads to loss of epithelial cells of hepatopancreas.

Treatment: there is no particular treatment of this viral infection.

Prevention and Control: the best prevention measure is the screening the PL’s before stocking prawns in the pond.

Hepatopancreatic Parvo Virus (HPV) Disease:

This is Caused due to parvo virus.

Symptoms: The major symptoms are Loss of appetite, low growth rate, discolored body surface and gill fouling with ciliates and opacity of abdominal muscles. Severe infections show whitish and atrophied hepatopancrease, anorexia and reduced preening activity.

Treatment: there is no treatment for HPV infection.

Prevention and Control: there are prevention methods for this disease, but the screening the PL’s before stocking prawns in the pond is recommended.

Read: Fish Farming Faq.

Yellow-head Disease (YHD) of Shrimp / Prawn

Symptoms: the infected prawn shows loss of appetite, slow swimming, pale bodies, swollen cephalothorax with a light yellow to yellowish hepatopancreas and gills.

Treatment: There is no treatment for YHV infection.

Prevention and Control: the best method to prevent this disease by, disinfect the contaminated ponds and equipment’s with 30ppm and maintain proper water quality and nutrition level. 

White Spot Disease (WSD):

The dsDNA virus mainly causes this disease.

Symptoms: Infected prawn swims to the water surface and congregate at pond dike. You can observe white spots inside of the shell and carapace, accompanied by reddish discoloration of the body.

Treatment: There is no treatment for this disease.

Prevention and Control: Efficient pond management, proper nutritional fees, good quality of PL, reduction of possible carriers, avoid contaminated water into the pond and disinfectant equipment and utensils.

Infectious Hepatopancreatic and Lymphoid Organ Necrosis (IHLN):

The root cause of this disease is through viral etiology.

Symptoms: You can observe light pinkish to yellowish B of the cephalothorax region. Fouling is occurred by ciliate protozoan Zoothamnium. Blackened and necrotic hepatopancreas.

Treatment: There is no treatment for this infection.

Prevention and Control: Maintain standard levels of physico-chemical condition of the pond environment. To avoid bacterial and viral pathogen entering from outside, closed culture will prevent this disease successfully.

Read: Frequently Asked Questions About Pearl Farming.

Bacterial Infections in Prawn / Shrimp farming:

Luminous Vibriosis: Caused due Vibrio harveyi, Vibrio vulnificus.

Symptoms: The major symptoms are High mortality rate in young juvenile prawns. The infected prawns will swim to the pond surface and edges of ponds. Severe infection causes vertical swimming behavior. Presence of luminescent prawns in the ponds.

Treatment: Disinfection of pond water with Formalin (100-200 ppm). Treat the prawns withOxolinic acid (0.6 ppm) and Sarafloxacin (5mg/kg) through feed for 5 days.

Prevention and Control: Proper pond and water management. Use the source of reservoir for water intake.

Vibriosis:

This is caused due to Vibrio vulnificus, V. parahemolyticus, V. alginolyticus, V. anguillarum, V. damsella, V. fluvialis and V. mimicus.

Symptoms: High mortality rates, mainly seen in young juvenile prawn. Moribund prawn will show corkscrew swimming behavior at the edge of the pond. Reddish discoloration of juvenile prawn. You can also observe External Fouling, Black spots, and chronic soft shelling.

Treatment: Disinfection of inflow water with formalin 100-200 ppm. Treat the prawns with Anti-microbial preparation a through feed (Oxolinic acid 0.6 ppm and Sarafloxacin 5 mg/kg).

Prevention and Control: Proper pond and water management. Use the source of reservoir for water intake.

Fungal Infestation in Prawns / Shrimp:

Larval Mycosis:

Filamentous fungi of genus Lagenidium spp. and other filamentous fungi, such as Sirolpidium spp. and Haliphthoros spp.

Symptoms: Eggs and larvae are weak and appear whitish. Mortalities may reach 100% within two days. Fungal mycelium turn into the larval tissues and ramifies into all parts of the body and protrudes out of the body and develops into sporangia.

Prevention and Control: General hatchery management practices such as use of UV sterilized and filtered seawater, adequate water exchange etc., must be strictly followed. Rearing water, equipment used in the hatchery and all hatchery facilities must be thoroughly disinfected before restarting the hatchery operations.

Protozoan and Parasitic Infestation:

Black Gill Disease:

This is caused due to Fusarium spp.

Symptoms: Brownish to blackish discoloration on the gills of juvenile prawn.

Treatment: there is no treatment is available for this fungal infestation without harming the prawn pond

Prevention and Control: there are no particular measures for prevention and control. Proper management of the pond bottom and prevention of the entry of wild crustaceans into the pond, which may carry the pathogen, is the best measure to control this disease.

Surface Fouling Diseases in Prawn:

These diseases are caused due to various species of bacteria, algae and protozoa such as filamentous bacteria, Leucouthrix sp., Flavobacterium sp. and Zoothamnium sp.

Symptoms: The Infectedprawns show black/ brown gills or appendage discoloration or fuzzy/cottony appearance due to a heavy colony of the organisms. In case of severe infections, the affected prawn dies during the molting period.

Treatment: Treat the affected prawns with Chlorine and formalin are often used in case prawn display heavy infection.  Constant Changing of water can be the best method, which stimulates molting of the prawn in order to reduce the infestation.

Prevention and Control: Prevention and control of the occurrence of surface fouling disease are done through maintaining proper sanitary conditions at the pond bottom and the overall pond area. Organic matters and suspended solids in the pond should be controlled to prevent the growth of those fouling organisms. This is achieved by changing the water or applying lime at regular intervals.

Microsporidosis (Cotton Shrimp Disease or Milk Shrimp Disease): Infected due to Thelohania spp., Nosema spp., and Pleistophora spp.

Symptoms: the infected prawns appear opaque and cooked. Gradual and low levels of mortalities are observed. Microsporidia occupies and replaces gill, muscle, heart, gonads and hepatopancreas, and cause necrosis in these regions.

Prevention and Control: Maintain proper sanitary conditions at the pond bottom and the overall pond area. 

Non-Infectious Diseases in Prawn / Shrimp:

Soft-shell syndrome:

The root cause of the soft-shell syndrome is no really known. But the low saline condition in the culture pond and deterioration of pond bottom conditions are some physico-chemical factors that causes this disease. When the Prawns fed with a low protein diet, contamination through agricultural run-off, high soil pH, low water phosphate and low organic matter in soil all have an impact on soft-shell disease.

Symptoms: The infected prawns look very weak, usually off-feed, have a loose thin exoskeleton. The Rostrum is stiff as healthy prawns. Wavy undulating intestine is clearly visible.

Prevention and Control: The best preventive measures are Low stocking density, feeding with high quality feed and frequent water exchange will reduce the recurrence of the disease.

Bottom Line of Shrimp Diseaases:

If you you fail to control any of the shrimp diseases in commercial aquaculture, you may incur heavy losses.

Read: Raising Free Range Chickens.

Last Updated: November 28, 2018