Brooklynella – Marine Fish Diseases and Treatment

Brooklynella hostilis

What You Need To Know:

* This is most often seen in clownfish, but it can afflict any fish. The fish’s skin will appear to be peeling or sloughing off, oftentimes causing excessive white mucous to form around the affected area(s).
* Treatment of choice is a 45 minute formalin bath (e.g. Quick Cure), followed by transfer into a new/sterile QT.
* The fallow (fishless) period for starving Brook out of a Display Tank is 6 weeks.

Early stages:

More advanced stages:

Brook on a Naso Tang (notice how it presents differently on non-clownfish): index.php And on this Purple Tang: Purple Tang Brook 3.jpg
Additional Information

Brooklynella hostilis is a ciliate parasite with a direct life cycle: It lives, feeds and reproduces directly on the fish (no encysted stage). However, there always exists the possibility that parasites can drop off into the water column and infect other fish. Having no encysted stage makes this pathogen easier to eliminate, but do not underestimate how fast killing Brook can be. Especially with clownfish.

Treatment Options – Formalin is the most effective treatment for Brook, but using Ruby Reef Rally is another good option. Both are best applied via bath treatment, and more information on this can be found in the links below.

Formalin (45 min bath): https://humble.fish/formalin/

Rally (90 min bath): https://humble.fish/acriflavine/

Post bath, transfer the fish into a clean/sterile QT to prevent reinfection. It is a wise course of action to dose Chloroquine Phosphate once (60 mg/gal) or metronidazole every 48 hours for 10-14 days thereafter. This is an “insurance policy” to ensure all of the parasites have been eliminated.

A 5 minute freshwater dip may provide temporary relief if you are unable to locate any of the aforementioned medications right away. Some even claim total eradication of the disease is possible just by performing multiple freshwater dips on the fish. Again, transfer the fish into a new/sterile QT following each freshwater dip to prevent reinfection.