Fishing with Brooklynella

How to Treat Brooklynella Disease in Fish

Brooklynella hostilis is a highly infectious and lethal illness caused by a marine parasite found in fish that may also be found in farmed and aquarium fish. The parasite assaults the gills, making breathing difficult. It is poisonous to fish and can kill them within hours to days. While Brooklynella may harm any fish, it is most closely and usually connected with the Amphiprioninae (clownfish) subfamily of the Damselfish family, and is hence generally known as illness. To be successful, treatment must be given as soon as feasible. If your fish are gasping for oxygen at the waterline, have mucus on their bodies, have skin sores, or scrape themselves on things in the tank, seek care from an aquatic veterinarian right away.

What Is Brooklynella?

The ciliated protozoan Brooklynella hostilis causes Brooklynella, a deadly illness that infects marine fish by attacking their gills and causing a buildup of mucus. These parasites dwell on the skin of fish and can infect the gills, causing serious respiratory issues. They resemble kidney bean-shaped parasites with cilia when seen under a microscope. Although this parasitic scourge is comparable to other aquatic parasites, it is dependent on a fish host to exist and is not picky in its search for a suitable host. Brooklynella is known to afflict clownfish and members of their scientific family, although it can infect any type of fish.

Symptoms of Brooklynella in Fish

Brooklynella, like Oodinium, is a parasitic parasite that affects the gills first. Your fish may exhibit the following signs once infected:


  • Mucous and lesions on the skin
  • Gasping for air
  • Scraping against objects in the tank
  • Lethargy and loss of appetite

Fish may scrape against surfaces at first, then develop fast respiration and gasp for oxygen at the surface when their gills get blocked with mucus. The fish will rapidly grow sluggish, refuse to feed, and lose its color. The most visible distinction between Brooklynella and Oodinium is the large volume of slime generated by a fish infected with this parasite. A thick, often white-colored mucus covers the body as the condition advances. This often begins at the head and spreads throughout the entire body. Skin sores can develop, and symptoms of secondary bacterial infections, such as redness and fin rot, are fairly uncommon.

Causes of Brooklynella

Brooklynella is always caused by Brooklynella hostilis, but fish can contract this parasite from a variety of sources. The following may cause your fish to develop the disease:

  • Close contact with infected fish
  • Infested fish being introduced to the aquarium
  • Contaminated water

Other species that can host Brooklynella parasites include angelfish, tangs or surgeonfish, wrasses, jawfishes, seahorses, and many others. The protozoa that cause this illness replicate asexually by conjugation utilizing simple binary fission, which allows them to grow more faster than Cryptocaryon (Marine Ich/White Spot Disease) and Oodinium (Velvet/Coral Fish Disease). Brooklynella's fast replication explains why it may kill fish in a matter of days. It can sometimes kill within hours of the onset of symptoms. As a result, timely identification and treatment of all fish exposed to these life-threatening parasites are essential.

Diagnosing Brooklynella in Fish

Brooklynella can mimic the signs of other illnesses, including as bacterial infections, which produce white, cloudy-looking skin on fish. As a result, any extra symptoms should be kept an eye on. Your fish's respiratory problems will most likely be determined by your aquatic veterinarian. Brooklynella can be confirmed as the source of symptoms by examining biopsies collected from the skin under a microscope.


There are a variety of recommendations for treating a Brooklynella-infested aquarium. Copper, malachite green, and other therapies are indicated, with some of them being used in combination with formaldehyde. The best and most successful therapy for Brooklynella is formaldehyde alone, according to most experts.

Formalin is a 37 percent formaldehyde gas solution in water with the addition of methanol as a stabilizer. It has been discovered to be a successful therapy for Brooklynella and other parasite disorders. However, formalin is a highly strong substance that should be handled with caution. Make sure you understand how to treat ich-infected fish with formalin so you can follow the instructions and take the necessary precautions. In a separate treatment container, a typical formalin solution is combined with either fresh or saltwater. Initially, all fish are given a brief dip in a greater concentration of formalin, followed by a longer treatment in a quarantine tank with a lower concentration of formalin (QT). The more time the fish are exposed to the formalin therapy, the more effective it will be in curing the condition.

If a formalin solution is not accessible right away, a might be used to offer temporary relief. Although this treatment will not cure the ailment, it can help to eliminate certain parasites and decrease mucus in the gills, which can help with breathing issues. After the initial dip or bath, place the fish in a QT with a to assist prevent any additional free-swimming protists from infecting the fish, and then start therapy as soon as possible.

Prognosis for Fish With Brooklynella

Brooklynella is very infectious, thus any fish that has been exposed to it should be removed from the aquarium and tested by an aquatic veterinarian. Because this disease spreads so quickly, many fish infected with these parasites die. A formalin solution, on the other hand, can be quite effective in removing parasites and preventing mortality provided the signs are recognized early enough and treatment started right once. In a quarantine tank, these treatments must be repeated every two to three days for at least three weeks, although some fish may have more serious infections that are lethal.

How to Prevent Brooklynella

While Brooklynella cannot be totally prevented, aquarium owners can take a few preventative measures to help lower the risk of this parasite affecting their tank:

Purchasing Well-Maintained Fish

Buying only well-maintained, captive-bred aquarium fish is one approach to avoid Brooklynella infesting your tank. Because it was most usually detected in clownfish, Brooklynella was initially known as clownfish sickness. This illness is common in wild-caught clownfish, but it is uncommon in captive-bred clownfish. Always attempt to work with sellers who maintain the best health tests and living circumstances for their fish when purchasing any species to introduce to your aquarium.

Quarantine New Fish

Any new aquarium fish should be quarantined for two to four weeks in a separate tank before being introduced to your aquarium. If any symptoms appear, do not put these fish in a tank with any other fish. Along with quarantining new fish, a freshwater plunge is also good. Because many parasites may be eradicated at least partially during five-minute dives, this will assist guarantee that only healthy fish are introduced to an aquarium.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.


"Parasitic Diseases Of Fish. Veterinary Manual" ;