Brooklynella in fish

Brooklynella is a fatal disease that is highly contagious and it's caused by a marine parasite. It affects Marine fish by attacking their gills, Making it impossible to breathe and creating a build-up of mucus. Brooklynella can affect any species of fish. It is most closely related to clownfish species.

Symptoms of Brooklynella in a fish

  • Gasping for air
  • Scraping against objects in the tank
  • Mucous and lesions on the skin.
  • Refuse to eat and its colors will fade.

What are the causes of Brooklynella in a fish?
Brooklynella is always caused by Brooklynella hostilis. It is caused by a marine parasite found in fish that can also be present in farmed fish and aquarium fish. Brooklynella hostilis is a parasite of Marine fish.

Here are some causes of Brooklynella in a fish are-

  • Close contact with infected fish.
  • Infested fish are being introduced to the aquarium.
  • Contaminated water.
  • Bacterial infections also cause white, cloudy-looking skin on fish.

Treatment of Brooklynella in a fish

Once you've diagnosed Brooklynellosis, prompt treatment is essential. Move the affected fish to a quarantine tank, and begin treatment with formalin.

They range from adding copper, malachite green, and other remedies, with some of those recommended being used in conjunction with formaldehyde. Formalin is a 37% solution of formaldehyde gas dissolved in water with methanol added as a stabilizer. It has been found to be an effective treatment for Brooklynella as well as other parasitic diseases.

The best treatment is prevention. Any new aquarium fish should be quarantined in a separate tank for two or four weeks prior to being placed in your aquarium. If any symptoms begin to present, avoid placing these fish in a tank with any others. A freshwater dip is also beneficial along with quarantining new fish. This will help ensure that only healthy fish are introduced to an aquarium, as many parasites can be at least partially removed during dips that last up to five minutes.

How to diagnose Brooklynella in a fish? 

If your fish displays any symptoms like gasping for air at the waterline, mucous on their bodies, skin lesions, or scraping themselves against objects in the tank, help should be taken immediately from an Aquatic veterinarian. This might be Brooklynella disease in your fish.

Brooklynella in Clownfish

Brooklynella is a parasitic infection typically associated with the Amphiprion family of fish, which is why it's often referred to as clownfish disease.

Common symptoms of Brooklynella in clownfish are

  • Sloughing or shedding of skin.
  • Furry mucus coating on the gills.
  • Loss of appetite.
  • Respiratory problems.

Treatment must be fast and effective, it typically requires isolation of the ailing fish and administration of antibiotics medication.


Make sure to purchase only well-maintained captive-bred clownfish from a reputable breeder. Since this disease is more common in wild-caught clownfish.

Another way to prevent Brooklynella is to quarantine new fish in a separate tank for a week prior to introducing them to the main aquarium. This way, if you notice any early signs of the disease, you can eradicate it in advance.

Giving new fish a quick freshwater dip prior to adding them to the main tank is also recommended. Anything you can do to ensure only healthy fish are introduced to your aquarium will go a long way in ensuring the Aquatic environment remains safe and disease-free.

Can a clownfish with Brooklynella heal on its own?

Brooklynella is a progressive disease that won't go away on its own. It must be treated promptly and completely otherwise death is imminent within a Matter of weeks. An ailing Clownfish should be isolated and then medicated with an appropriate antibiotic such as formalin.