Black Fungus (phaeohyphomycoses) on Smelt

Observation: Years have passed since we started seeing these kind of marks on fish that are caught and nobody knows whats causing the marks to show up on them. We don't really know if other surrounding villages have the same problem with their catches. These smelt were caught near the mouth of the Kugkaktlik River, about ten miles downriver from the village of Kipnuk.

Alaska Department of Fish & Game Consult: "This is the black fungal condition that occurs in saffron cod (not tom-cod) that we are very interested in studying. It’s unfortunate that we couldn’t get any samples due to the delay in viewing the photo/consult. We have received anecdotal reports of it occurring in “smelts” or “hooligan”, so the photos you sent are helpful for supporting that it can occur in fish from the smelt family Osmeridae. It’s difficult to tell the exact species of smelt in the two photographs that you sent and they appear to possibly be two different species. The photograph of the fish with only the anterior portion of the body in tact resembles a rainbow smelt whereas the photograph of the whole fish with an open mouth more resembles a capelin."

Regarding the implications for human health and the safety of consuming these fish, Dr. Ferguson writes: "Some of the black fungi are capable of infecting people, especially those with immunosuppression. Some of the black fungal species also produce mycotoxins that could represent an allergenic threat. Please note that these fungi are commonly present in the environment, for example, Chaetomium grows inside homes on water damaged roofs, ceilings, walls and carpets. The large infection that occurs on these fish likely contains large numbers of these organisms. It would be best to take a conservative approach and not eat the fish. Given the very unappealing presentation of these fish, good common sense would also support this course of action."

Regarding information on this condition, I have attached a short chapter that is a draft for our next edition of our fish disease book:

BLACK FUNGUS FROM FISH IN NORTON SOUND & SOUTHWESTERN ALASKA

• Black fungus of saffron cod (tomcod)
• Skin and gills
• Confirmed from saffron cod (tomcod), but reported from smelt (hooligan) too
• Numerous reports from Norton Sound and surrounding area over the years (since 2005)
• Unalakleet, Nome, Snake River, Nightmute, Shaktoolik River,

• Isolated several species of fungus from the same related group (Ascomycetes)

  Clinical Signs

• Large (1 X 2 cm), black lesion that is firm with a wrinkled texture (Figure 2 below)
• Gill infections – smaller black lesions
• No internal lesions
• Fish apparently feeding normally
• Lesions likely result in chronic debilitating condition that could lead to death in fish.

Transmission - Commonly found in environment – wood, plants, soil, air - Ascospores likely come in contact with damaged tissue (but mechanism unknown) - Mostly reported in late fall months (Oct – Nov), but some reports as late as Feb.

What to do if seen = please contact Anchorage Fish Path Lab - (907) 267-2394 - Jayde.ferguson@alaska.gov - Photographs can be used to preliminary diagnose - If warranted, fresh (not frozen) sample of lesion could be sent - ADF&G can pay for shipping costs

LEO Network has also copied this posting to the Environmental Health Department at the Yukon Kuskokwim Health Corporation, Sea Grant Marie Advisory Program Agents, and to Environmental Health staff at ANTHC.