Brooklynella Disease Diagnosis and Treatment

Clownfish resting in anemone
Photograph by Mikael Kvist/ Moment/Getty Images

What Is Brooklynella?

Brooklynella is a type of saltwater ich caused by an infestation of the ciliated protozoan Brooklynella hostilis. It is most closely and commonly associated with subfamily Clownfish members of the Damselfish family, and therefore is typically referred to as Clownfish Disease. Although this parasitic scourge similar to others requires a fish host to survive, it is not particular in its quest to find one. Angelfishes, tangs or surgeonfishes, wrasses, jawfishes, and seahorses among others will host Brooklynella.

These protozoa reproduce asexually using simple binary fission through conjugation, which is why they can multiply so much more rapidly than Cryptocaryon (Marine Ich/White Spot Disease), and Oodinium (Velvet/Coral Fish Disease), and why it can kill fish within a few days. Sometimes, it can kill mere hours after you notice it. For this reason, accurate diagnosis and immediate treatment of all fish exposed to these life-threatening organisms are critical.

Symptoms to Look For

Most similar symptomatically to Oodinium, this too is a parasite that primarily attacks the gills first. At the onset fish may scrap up against objects, rapid respiration develops, and fish often gasp for air at the surface as the gills become clogged with mucus. Fish become lethargic, refuse to eat, and colors fade, but the most noticeable difference that sets Brooklynella apart from ​Oodinium is the heavy amount of slime that is produced. As the disease progresses a thick whitish mucus covers the body, usually starting at the head and spreading outward, skin lesions appear, and it is not uncommon for signs of secondary bacterial infections to arise.​

Treatment Recommendation

Suggestions range from copper, malachite green and other remedies, with some recommended being used in conjunction with formaldehyde. However, the consensus is these types of medications are either largely ineffective or do not work at all, and that the best and most effective treatment for Brooklynella is formaldehyde alone. Typically a standard 37% formalin solution (shop & compare prices) is mixed with either fresh or saltwater in a separate treatment container. Initially, all fish are given a quick dip or a prolonged bath, followed by continued treatment and care in a QT. Of course, the longer fish are exposed to the formalin treatment, the more effective it will be at eliminating this "disease." Whether to administer a dip or a bath to start with is something you will have to determine yourself, but there's a very simple way to do this.

Formalin is a brand name of a form of Formaldehyde and has been found to be an effective treatment for Brooklynella as well as other parasitic diseases. However, formalin is a very powerful chemical and should be used very carefully. See How to Treat Ich Diseased Fish with Formalin for instruction and further cautions.

Urgent Treatment Tip:

If a formalin solution is not available for immediate use, temporary relief may be provided by giving fish a freshwater dip or bath. Even though this treatment will not cure the disease, it can help to remove some of the parasites, as well as reduce the amount of mucus in the gills to assist with respiration problems. Once the initial dip or bath is done, place the fish into a QT under hyposalinity treatment to help keep any possible new free-swimming protists from infecting the fish again, and then obtain a formalin medication as soon as possible to begin treatment.