''Brooklynella hostilis'' is a

parasite Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the Host (biology), host, causing it some harm, and is Adaptation, adapted str ...

of marine fish, found in wild fish, farmed fish and aquariums. It is kidney-bean shaped, and approximately long, with bands of

cilia The cilium (: cilia; ; in Medieval Latin and in anatomy, ''cilium'') is a short hair-like membrane protrusion from many types of eukaryotic cell. (Cilia are absent in bacteria and archaea.) The cilium has the shape of a slender threadlike proj ...

. It reproduces by

binary fission Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two values (0 and 1) for each digit * Binary function, a function that takes two arguments * Binary operation, a mathematical o ...

. ''B. hostilis'' causes the disease Brooklynellosis, also known as slime-blotch or clownfish disease. In

marine aquarium A marine aquarium is an aquarium that keeps marine plants and animals in a contained environment. Marine aquaria are further subdivided by hobbyists into fish only (FO), fish only with live rock (FOWLR), and reef aquaria. Fish only tanks ofte ...

s, ''B.hostilis'' infects most

teleost Teleostei (; Ancient Greek, Greek ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as teleosts (), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all neontology, extant species of f ...

s (ray finned fishes). ''B.hostilis'' feeds on dead skin cells and can cause severe damage to gills. Affected fish have a gray discoloration, and may breathe abnormally fast or abnormally slow. The infection can cause sloughing of skin, and congestion of the gills. The parasite spreads rapidly, and can easily transfer to a new host.

Formalin Formaldehyde ( , ) (systematic name methanal) is an organic compound with the chemical formula and structure , more precisely . The compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde. It is stored as ...

is an effective treatment.

References

Phyllopharyngea Parasites of fish Veterinary parasitology Ciliate species Protists described in 1970 {{Alveolata-stub