Tobiassorensen
Vancouver_98683
Thank you guys so much for your help. I had no idea what this is and never heard of the epistylis, which appears to be a protozoa.
Striped Bass and Other Morone Culture
John A. Plumb, in
Developments in Aquaculture and Fisheries Science, 1997
11.6.2.2 Epistylis
There are several species of
Epistylis that infect the skin, fins, and
gills of fish (Esch et al., 1976). The urn shaped organism, which is adorned by a ring of
cilia on the distal end, is at the terminus of a dichotomous stalk that, in turn, attaches by a disk to hard surfaces of the host such as spines, scales, or
gill covers. Groups
of Epistylis form a colony (Figure 11.11). These
parasites cause
irritation and inflammation of the
epithelium of the host at the point of
attachmentwhich may provide a site for secondary infections of
Aeromonashydrophila. The parasites feed primarily on bacteria and organic material in the water, but they erode scales and hard spines of fins where they attach. Other than the injury incurred by attachment, they are seldom harmful to the host unless there are large masses of these parasites.
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https://www.adfg.alaska.gov/static/species/disease/pdfs/fishdiseases/epistylis.pdf
Epistylis (Heteropolaria)
I. Causative Agent and Disease
Epistylis is a sessile, ciliated freshwater protozoan that propagates as colonies at the ends of non-contractile stalks on the skin and sometimes the gills of fish. This organism is not a true parasite but an epibiont utilizing fish as a substrate for attachment that will cause tissue necrosis from secreted proteolytic enzymes. This biofouling and tissue damage results in osmoregulatory stress and secondary invasion by opportunistic bacteria and water molds. This protozoan exists worldwide.
II. Host Species
All species of salmonids are susceptible, but infestations are more common in catfish and other warmwater fish species including their egg masses.
III. Clinical Signs
Flashing is a nonspecific sign of external attachment by any parasite or epibiont. Infested fish may also produce excessive external mucus and exhibit white or hemorrhagic lesions.
IV. Transmission
This organism reproduces by binary fission and is horizontally transmitted from fish to fish by transformation of the zooid (bell shaped body) into a discshaped ciliated telotroch. Slow water flows with high organic loads and abundant bacteria on which it feeds favor the colonization of this protozoan.
V. Diagnosis
Diagnosis is made by observation of the live protozoan in wet mounts of skin scrapes. The colonies appear like a cluster of bluebells growing on stalks attached to the fish by a disc. Epistylis has branched non-contractile stalks.
VI. Prognosis for Host
The prognosis for an infested fish is good if organism numbers are low and fish are not stressed. Heavy colonial growth in a hatchery setting must be treated with salt or chemicals (formalin or hydrogen peroxide) to reduce numbers of protozoa and prevent secondary infections by bacteria and water molds. Infestation is a sign of poor water quality that should be improved.
VII. Human Health Signifcance
There are no human health concerns associated with Epistylis.
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http://fisheries.tamu.edu/files/2013/09/SRAC-Publication-No.-4701-Protozoan-Parasites.pdf
Epistylis and Heteropolaria
The protozoan parasites Epistylis and Heteropolaria are very similar. They are single-celled, but live in stalked colonies (Fig. 9). The branching stalks are rigid and do not contract; the cells at the ends of the stalks are called zooids. They contain cilia around the oral opening and contract when feeding. Epistylis or Heteropolaria colonies on fish resemble white tufts of fungus (Fig. 10), but can be differentiated from fungus by microscopic examination. These parasites are usually found on the skin and fins. The base of the stalk attaches to a hard, calcified surface such as scales and fin rays or spines. Epistylis and Heteropolaria reproduce by budding and form a teletroch or motile juvenile stage. The teletroch produces a stalk and uses it to attach to an existing colony. Epistylis is often an ectocommensal in that it simply attaches to the fish and feeds on environmental debris such as bacteria. Poor quality water encourages the growth of Epistylis on fish. These parasites can weaken and kill fish. Ulcers caused by Epistylis infections may make fish more vulnerable to bacterial infections. For example, red sore disease involves the combination of Aeromonas bacteria and Epistylis. The classic treatment for Epistylis and Heteropolaria infections is uniodized salt (sodium chloride).