COMMON DISEASES ON PANGASIUS (Pangasius hypophthalmus)

In recent years, aquaculture has developed strongly, contributing significantly to the growth of the economy and becoming one of the leading economic sectors in Vietnam some tropical countries. Pangasius grow fast, have a good quality of meat and are highly adaptable to harsh environmental conditions that’s why Stripped catfish is a popular species that are cultured in Asia, particularly in some countries like Thailand, Laos, Cambodia, India, Bangladesh,…

Pangasisus has commercial stripped catfish farm bring to the high economic. For this reason, the farming area has been constantly expanded and the stocking density is also increased. Therefore, this is the chance for infectious diseases outbreaks to occur more and more in most Stripped catfish farms. In recent years, the production and consumption of Stripped catfish are facing many difficulties and challenges due to uncertain prices, unstable export markets and making fish diseases happen. It is an extremely serious problem and has become the top concern of Strippes catfish farmers.

The article aims to provide clear pathological signs, to help pangasius farmers to detect early signs of infection and safe and effective treatment methods.

1.Bacillary necrosis of Pangasius (BNP) disease

Bacillary necrosis of pangasius (BNP) is one of the most serious diseases and affects strongly to the economy of Pangasius farmers.

The disease occurs in all ages of fish, although high mortalities are reported in fingerlings and juvenile fish. Outbreaks decrease production and increase costs associated with treatment and high fish mortalities. The mortality may be more than 90%.

- Causative agent: Edwardsiella ictaluri

- Clinical sign: Numerous white spots appear on the kidney, spleen and liver. The internal organ is hemorrhagic

White spots appear on the liver, kidney and sleen

- Treatment:

+ Change 20- 30% water in the pond, use Vimekon ( 1kg/1500- 2000 m3) or Vime-Protex ( 1L/2000 m3)

+ Mix 1L of Forfish and 1.5kg Doxery concentrated to the feed for 20 tons of fish or 1L of Forfish + 2kg Amoxi concentrated for 20 tons of fish in 5-7 consecutive days

2. Hemorrhagic disease

This infection often occurs at the change from dry to rainy season, especially during periods when fish are stressed during handling and transportation. Reducing stocking density and maintaining high-quality health management can significantly reduce the incidence of this bacterial problem in fingerlings and grow-out fish in ponds.

- Causative agent: a group of motile Aeromonas species – Aeromonas hydrophila, A. sobria and A. caviae or Pseudomonas flurescens, Streptococcus spp.

- Clinical signs: The gross clinical signs associated with the condition are the presence of hemorrhages on the head, mouth and base of fins; a red, swollen vent; and pink to the yellow fluid. Sometimes gas in the gut can be observed.

Hemorrhages on the head, mouth, fins and internal organ

- Treatment:

+ Pond water treatment by Vime-Iodine 1L/2000-3000 m³ or Vime -Protex 1L/2000-3000 m³

+ Mix to the feed 1L Norflovet + 1L Vime-Fenfish 2000 for 20 tons of fish or 1L Norflovet +2kg Amoxi concentrated for 20 tons of fish in 5-7 consecutive days

+ Use Anti - Shock 3-5g/ kg of feed combine with Vitamin C antistress 1kg/200-300kg of feed to enhance the immune system and release stress.

3. White gill and liver

Due to the high-dose antibiotic-fed breeders accumulate in the liver; make the liver is less active, fish become anemic, fish gills cannot get oxygen to transport blood to supply the body. The mortality is more than 60-70%

Clinical signs:

- Weak activity, swims slowly

-Secretes lots of mucus on the body

- The gills gradually change from red to pale pink and white

-The internal organs are pale, the liver also turns pale yellow or cream, the stomach has no food and there is little fluid in the internal sinuses.

Gills gradually change from red to pale white

Treatment

- Water treatment by Freshwater 1kg/1500-2000n m3 or Protectol 1L/1500-2000m3

- Mix to the feed with Liver ( 1L/10 tons of fish) and Sorpherol 1kg/30-40 tons of fish about 5-7 consecutive days.

4. Protozoa disease by Myxobolus

The disease often occurs in commercial catfish ponds from fingerling to fish, it occurs all year round, not seasonally like some other parasite groups.

- Causative agent: Myxosporidae sp

- Clinical signs

+It had no obvious pathological signs, only saw scattered dead fish every day. In severe infected fish samples, there are often signs of bacterial disease (purulent liver and kidney, hemorrhage, jaundice...) and the abdominal skin is perforated with tiny holes or with some very large holes.

+The internal organs are normal and in a few infected fish, there is pale bile. The size of the cysts ranges from 0.5 to 3 mm depending on the size of the fish, sometimes forming cavities larger than 3 mm filled with milky white fluid (fragile) in fish weighing more than 500 grams, the cysts can be found with the naked eye.

A. Spore in fish’s intestine B. Spores in fish’s muscle C. Holes on fish’s skin D.Myxobolus spp.

- Treatment:

Disinfect the pond with Protectol 1l/1500-2000m3 or Vime-Protex 1L/1500-2000 m3, 1 time every 4 days.+ Treat by Vimax 1L/30-40 tons of fish/day or Vime-Clean 1kg/20 tons of fish/day+ Add Vitamin C- Antistress( 1kg/200-300 kg of feed)

5.Red Spot disease

- Causative agent:

+ Bacteria: Aeromonas hydrophyla, Aeromonas sobria, Pseudomonas fluorescens, Flavobacterium sp, Micrococcus sp, Vibrio sp, Nocardia sp...

+ Fungi: Fungi are not causative agents of the disease, but the fungal infection will increase the severity of the disease and increase mortality. Several species of fungi have been isolated from the sores of fish belonging to the genera

Aphanamyces, Achlya and Saprolegnia.

+ Other factors including several types of protozoan and multicellular parasites, environmental factors such as inappropriate water temperature, water pollution or nutritional deficiencies also contribute to the increased incidence of the disease.

- Clinical signs:

+ Lethargic fish float on the surface pond, stop feeding

+ Gray or red sores appear on the body, head, fins, caudal. The sores spread wide and swirl deep into the bone, the fish scales fall off leading to bleeding and inflammation.

- Treatment:

+ Water treatment by using Vimekon 1kh/2000m3 or Vime- Protex 1L/1500-2000m3

+ Mix to the feed with 1L of Norflovet and 1kg Doxery for 10 tons of fish or 1L of Norflovet and 1kg of Kamoxin F for 10 tons of fish in 5-7 consecutive days.

+ Add Vime- Glucan 5kg/kg of feed or Glusome 115 4g/kg of feed to help the fish increase their resistance and heal wound quickly.

6. Columnaris disease

The disease usually occurs when the rainy days are long, or because the pond contains a lot of organic humus, or because the pond is not properly improved before stocking.

- Causative agent: Flavobacterium Columnare

- Clinical signs:

The fish swims without orientation, secrete lots of mucus on the skin; the tail has many white spots, necrosis. In severe cases, the fish will have sores, wear off the tail, and eat deep into the muscle.

- Treatment:

- Water treatment by Freshwater 1kg/2000 m3

- Mix to the feed with 0.5kg Kamoxin and 250ml Vime- Fenfish 2000 for 5 tons of fish or 0.5 kg Kamoxin and 0.5 L Norflovet for 5 tons of fish in 5-7 consecutive days.

- Add Vime- Glucan 5g/kg of feed or Glusome 115 4g/kg of feed to enhance their’s immune system

7. Internal parasital disease

They harm fish in the commercial stage, at this stage the fish eat a lot and release the amount of waste is large. If not handled well, the water will be contaminated, creating conditions for the development of helminth larvae. This disease does not cause mass fish death but slows down the growth of fish.

- Causative agent: Philometra, Bucephalopsis, Acanthocephala, Bothricephalus…

- Clinical signs:

Fish grow slowly, head bigger than usual, slow-moving, pale skin. Parasitic worms damage the stomach and intestines, make the fish skin yellow, and the belly contains yellow fluid.

- Treatment: Mix to the feed

+ Kill-site 1kg/20 tons of fish

+ Vime -Clean 1kg/15-20 tons of fish or Vimax 0.5L/20 tons of fish

+ Using 1kg Sorpherol for 30 tons of fish, 1kg Figrow for fish for 20 tons off fish to improve the meat quality of fish

8.External Parasital disease

These species exist in very large numbers in almost all freshwater, salt and brackish water environments and are harmful to fish health because they use fish nutrients and have serious health consequences. fish health.

This disease is very common in both freshwater and saltwater fish farming, the harm it causes is also very serious such as causing unsightly fish, causing ulcers and even fish death if not detected and treated. timely handling.

- Causative agent: Trichodina, Ichthyophthirius, Dactylogyrus, Gyrodactylas, Argulus…

- Clinical signs: fish grow slowly, swimming slowly, secrete lots of mucus on body and gill