In aquaculture, one of the serious threats that many farmers often face is Vibrios disease, which can occur in many aquatic species such as fish, shrimp, clams, and more. This disease develops strongly when the water environment deteriorates, stocking density is high, or the resistance of aquatic animals is reduced. In this article, Vemedim will provide information to help farmers and aquaculture producers gain a deeper understanding of the disease and how to proactively respond to keep their stock healthy and their production cycle effective.
Causes of Vibrios disease in aquatic animals
In aquaculture, the health of fish and shrimp stocks is always a top priority to ensure productivity and product quality. However, one of the serious threats that many farmers often encounter is disease caused by Vibrio spp., which can affect many aquatic species such as fish, shrimp, clams, and more.
This disease develops strongly when the water environment deteriorates, stocking density is high, or the resistance of aquatic animals is reduced, and there is currently no definitive specific treatment. The main cause of the disease is bacteria of the genus Vibrio, a group of Gram-negative, straight or slightly curved rod-shaped bacteria that do not form spores and move by means of one or more slender flagella.
They live mainly in seawater, estuaries, and aquaculture tanks. Vibrio spp. are facultative anaerobic bacteria capable of oxidizing and fermenting glucose in O/F medium. Vibrio species can survive in seawater and associate with aquatic animals; some are opportunistic pathogens that cause severe disease when stock is stressed, weakened, or infected with other agents.
Some common Vibrio species that cause disease in aquaculture include:
- V. alginolyticus – causes red streaks along the body in black tiger shrimp larvae.
- V. anguillarum – causes septicemia in fish.
- V. parahaemolyticus – causes luminescent disease in black tiger shrimp larvae.
- V. harveyi, V. vulnificus – associated with red body disease, shell erosion in crustaceans, and septicemia.
- V. salmonicida – causes disease in fish in cold-water regions.
Vibrio spp. are commonly found in both marine and freshwater aquaculture: fish, shrimp, crabs, and mollusks. They are often opportunistic pathogens, proliferating strongly when stock is stressed by environmental changes, viral or parasitic infections, or weakened immunity.
The bacterial count in nursery tanks increases over the culture period and is higher at the bottom layer; therefore, bottom siphoning helps reduce Vibrio density. The disease occurs sporadically or in outbreaks depending on the species, season, and environmental conditions.
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Typical symptoms of Vibrios disease
Vibrio spp. cause disease with different symptoms depending on the species and developmental stage:
Symptoms of Vibrios disease in cage-cultured fish and brackish-water ponds
- Hemorrhagic spots appear on the body, eyes become cloudy or blind, and the liver has white spots.
- The symptoms of Vibrios disease are similar to septicemia caused by Aeromonas spp.
Symptoms of Vibrios disease in shrimp and crabs
- Floating on the water surface, drifting to the shore, or swimming in circles abnormally.
- Comatose, lethargic, reduced feeding, or complete loss of appetite.
- Changes in body color (red or blue), soft shell, erosion lesions, and necrosis on the body and appendages such as antennae, walking legs, swimming legs, and tail.
- Shrimp larvae infected with V. parahaemolyticus or V. harveyi may become luminous.
- Red spots appear at the base of the antennae, cephalothorax, and body when infected with V. alginolyticus.
- In crabs with Vibrios disease, clotted blood appears 24–48 hours after Vibrio spp. infection, including blood cells and bacteria.
Prevention and treatment of Vibrios disease
To limit Vibrios disease, farms should apply the following measures:
- Filter water through sand and treat it with ultraviolet light before it enters the tank.
- Treat broodstock shrimp with Formalin 20–25 ppm for 30–60 minutes.
- Disinfect algae with Copperal - an organic copper product that kills toxic algae and treats pond slime algae.
- Treat Artemia with Chlorine 10–15 ppm for 1 hour, then rinse thoroughly.
- Spray EDTA 2–5 ppm into nursery tanks to suppress bacteria.
- Perform regular bottom siphoning, especially in larval nursery tanks.
- During the Zoea–Mysis stages, disease prevention can be carried out by disinfecting the water source with Vemedim Vime-Protex.
- In severe outbreak cases, destroy the production batch and treat with Chlorine 200–250 ppm for 1 hour before discharging water into the environment.
Vibrios disease can be treated effectively with the following methods:
- Use antibiotics in larval nursery tanks:
- Oxytetracycline + Bacitracin (1:1), 1–3 ppm.
- Erythromycin + Rifamycin (5:3), 1–2 ppm.
- Erythromycin + Bacitracin (1:1), 1–3 ppm.
- Apply directly after 12 hours of water exchange, and continue treatment for 3 days.
- For market-size shrimp: mix antibiotics with formulated feed according to professional guidance.
Vibrios disease caused by bacteria in aquatic animals can cause serious damage if not well controlled from the outset. Proactively implementing preventive measures and timely treatment at the first signs will significantly reduce the risk of spread and losses. With experience and professional support solutions from Vemedim, farmers can confidently work together to protect their stock, improve production efficiency, and move toward a sustainable farming model.
