Blackening of Discus Fish: Cause and Solution

Posted by HANGSHAKALI CHAKRABORTY on

BLACK COLORATION DISCUS FISH

Blackening of Discus Fish

  • Discus fish develop Black Spot on their body.
  • The development of black spots reduces the beauty of the fish.  
  • The developments of black spots are also known as Black Peppering Effect

Factors responsible for the Blackening of Discus Fish

Either of two factors is responsible for the blackening effect:

  1. Due to Black Background of Aquarium:  Non-fatal
  2. Due to Viral Infection: fatal

NORMAL CONDITION OF DISCUS (DAY 1): NO BLACKENING/PEPPERING 

 

SAME FISH SHOWING BLACKENING/ PEPPERING EFFECT (DAY 5): DUE TO ENVIRONMENT

How does the background of an aquarium cause the Black Peppering of the Discus fish?

  • Some Discus fish have the capacity to Camouflage
  • The Camouflage capacity makes them adjust themselves with their environment and in the presence of dark environments such as black background and bottom they show black peppering effect
  • The camouflage capacity of Discus fish is due to the presence of pigeon blood gene

How virus infection does cause mortality in the Discus fish?

  • The infection caused by the virus is known as Discus Plague or Black Disease
  • The infected fish have the following symptoms:
1. Initial symptoms:
  • Heavy breathing: 3 breaths per seconds
  • Loss of appetite: stop feeding
  • Black spots all over the body
  • Hiding at the corner of the aquarium
  • Excessive mucus/slime production
  • Scratching behaviour against hard objects in the aquarium
  • Suppressing immunity
2. Later Symptoms:
    • Later become vulnerable to Secondary pathogens like:
      • Parasites: Spironucleus spp, ichthyophthirius multifiliis etc.
      • Bacteria: Aeromonas hydrophila,
      • Fungus: Fusarium solani, F. oxysporum and F. moniliform
    • An infection like fin/tail rot begins
    • White patches are found
    • Smelly water
    • Mortality begins

The disease spreads rapidly from one tank to another in a short span of time (2-3 days).

Cure for the Diseases

1. Treatment for the blackening due to the environment:
    • By changing the dark coloured environment to white coloured environment
    • Best colour of environment: Light blue background and whitish bottom
    • With the blackish environment: the peppering effect in fish will increase with time
    • Black peppering effect may fade with corrective measures but may not go completely
    • Feeding with high-quality feed will help further
    2. Treatment for the blackening due to the virus: No cure but can be supportive:
        • Separate the affected fish immediately
        • Exchange water daily (10-40% depending on the severity of the environment and disease)
        • Provide quality feed and remove excess feed immediately
        • Treat with the AZOO Magic Treatment
        • Increase temperature to 30ᵒC
        • Cure the secondary infection using specific treatments recommended for them
        • 50-100% water exchange is recommended daily before adding new doses of drugs/aqua-medicines

      Guided by: Dr. Himadri Saha, Assistant Professor, Department of Aquatic health and Environment, College of Fisheries, CAU(I), Lembucherra. email: sahacofcau@gmail.com


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