Fish Diseases

by

Fish diseases can be caused by bacteria, viruses, and protozoa. Bacterial diseases include fin rot; viral diseases cause high mortality; protozoan infections, such as Ich, lead to white spots and respiratory issues. Proper management is essential to prevent outbreaks.

Some of the Fish Diseases

Bacterial Diseases in Fish :

Columnaris :

• Causative agent: Flexibacter columnaris; Flavobacterium columnar

• Symptoms:

  • (i) White spots on mouth, gill, edges of scales & fins
  • (ii) Fish fins disintegrate beginning at the edges.
  • (ii) Saddleback lesion near the dorsal fin.

•Treatment:

  • (i) Add aeg aquarius salt.
  • (ii) For external treatment of the fish using Acriflavine, Furan, Terramycin or Copper Sulphate.

Dropsy :

•Causative agent: Pseudomonas punctata

• Symptoms: 

  • (i) Belly swelled up, abdomen bulged largely.
  • (ii) Internal organs are affected mostly the liver and kidney.
  • (iii) Scales become loose.

• Treatment: The bacteria may be killed by applying Streptomycin or oxytetracycline along with supplementary food.

Furunculosis :

• Causative agent: Aeromonas salmonicida

• Symptoms:

  • (i) Appearance of bloody boils on the skin or muscle progressing to lesions.
  • (ii) Darkening of body colour and pale gills, blood discharges from nares.

• Treatment: Supply food containing antibiotics like introfurans or sulphonamides.

Fish Tuberculosis :

•Causative agent: Mycobacterium piscium

Enteric Red mouth Disease      

•  Causative agent: Yersinia ruckeri

Streptococcosis :

• Causative agent: Streptococcus iniae; S. agalactice

Francisellosis:

• Causative agent: Francisella noatunensis

Aeromoniasis :

• Causative agent: Aeromonas hydrophila

Viral Disease in Fish :

Spring Viremia of Carp :

• Causative agent: Rhabdovirus carpio

• Symptoms:

  • (1) Infected fish becomes black and develops lesions on skin and gills.
  • (2) Bleeding from scales, accumulation of fluid in the body.

• Remedy: There is no specific cure for this disease.

Protozoan Disease in Fish :

1. White spot disease or Ich Disease :

 • Causative agent: Ichthyophthirius multifiliis

• Symptoms:

  • (1) White, & cysts-like spots on the skin, fins and gills. 
  • (2) fins held close to the body. 
  • (3) Fish may rub against objects in an attempt to reduce irritation.

• Treatment:

  • (1) Increase the water temperature that can inhibit the life cycle of protozoa.
  • (2) Ich can be treated with formalin or copper based medications.

2. Marine Velvet Disease:

• Causative agent: Amyloodinium ocellatum

3. Costia or Slime Disease :

• Causative agent:  Ichthyobodo necator ; Costia neeatrix

• Symptoms:

  • (1) Excessive slime production on the skin and gills
  • (2) Respiratory distress and lethargy.

• Treatment: (1) Treat with formalin or other antiprotozoal medication 

4. Trichodiniasis :

• Causative agent: Trichodina sp. ; Trichodinella sp.

• Symptoms:

  • 1) Skin and gills are affected by the parasite infection.
  • 2) A sticky (slime) material oozes out from the body.

• Treatment:

  • (1) Isolate the affected fish and treat medications.
  • (2) Treat with formalin or other recommended antiprotozoal medication.

Terms used in Fisheries

Leave a comment