The 2025 EAFP Histopathology Workshop was held in conjunction with the 22nd International Conference on Diseases of Fish and Shellfish in Heraklion, Greece. The workshop convened on August 31, 2025, one day before the main conference on September 1–4, 2025. Organized by Barbara Nowak, Heike Schmidt-Posthaus, Patricia Noguera and Diane Elliott. This year’s workshop focused on finfish gill normal histology and histopathology, important topics in fish health and disease diagnostics.

The keynote presentation by Dr. Jeffrey Wolf addressed common artefacts and pitfalls in interpretation of histological sections of gills, emphasizing the need for continuous education and training in the specialized field of histopathology. The keynote address was followed by a number of invited presentations, including “Gill normal structure and common pathology” (Dr. Hamish Rodger), “Immune cells and structures in fish gills” (Professor Erling Koppang), “Melanomacrophages and melanin in gills” (Dr. Havard Bjorgen), “Pseudobranch – normal structure and pathology” (Dr. Johanna Baily) and “Gill neoplasms” (Professor Heike Schmidt-Posthaus). 

The workshop also included 14 case presentations covering a broad spectrum of host species and gill conditions associated with infections by a range of pathogens and non-infectious causes, as well as a “mystery case”. All histology slides for the case studies were digitized and the link provided to participants before the workshop. The link was scheduled to remain active until December 31, 2025, to allow further viewing. The workshop brought together 56 researchers, diagnosticians, educators, students and industry professionals from many parts of the world. Participants particularly appreciated the interactive format, which encouraged the exchange of experiences and discussion of challenging diagnostic cases.

The list below shows all the presentations provided during the workshop. Please note that the presentations posted are the originals submitted by the presenters and have not been edited or peer reviewed. For multi-author presentations, the underlined author was the presenter.

The access to the workshop proceedings is granted to active EAFP members only. Please click here to access available presentation files, upon login using valid credentials.

Keynote presentation:

• • Jeffrey Wolf – A Critical Review of Gill Histopathology Data from 100 Fish Toxicology Studies
    

Introductory Presentations:

• • Hamish Rodger – Gill Anatomy, Histology & Common Pathologies in Teleosts
  • Erling Koppang – Immune Cells and Structures in Gills
  • Håvard Bjørgen – Melano-macrophages and Melanin in Gills
  • Johanna Baily – The Pseudobranch
  • Heike Schmidt-Posthaus – Gill Neoplasms

Case Studies:

• • Roberto Bermúdez – Gill Neoplasms in Tench
  • Céline Möckli – Koi Herpesvirus (Cyprinid Herpesvirus III) in Koi
  • Sovomi Seibold – Flavobacterial Infection of the Gills in Rainbow Trout (Oncorhynchus mykiss)
  • Kai-Inge Lie and Helene Wisløff – Mycobacterial Branchitis in an Atlantic Salmon Smolt
  • Maria Constenla, Timur Izmaylov-Mirgasimov and Francesc Padrós – Epitheliocystis in Wild Fish
  • Stefania Vannetti and Xoel Souto – Case 1) Nodular Gill Disease in Swiss Rainbow Trout. Case 2) Amoebic Gill Disease in Spanish Turbot
  • Maria Constenla and Francesc Padrós – Nodular Gill Disease-like in Gilthead Seabream
  • Nicolas Diserens – Apicomplexa Infection of Unknown Origin in Brown Trout
  • Laura Muns – Aporocotyle spinosicanalis Eggs in Gills of Merluccius merluccius
  • Eva Lewisch – Microsporidian Gill Disease in Rainbow Trout
  • Francesc Padrós – Unexpected Ectopic Thyroid Follicles in Gills in Senegalese Sole (Solea senegalensis)
  • Mette Hofossæter, Marta Alarcón and Helene Wisløff – Case 1) Mortality in Fry Associated to High pH and Ammonia Toxic Exposure. Case 2) String Jellyfish Apolemia (Most Likely A. uvaria) Causes Serious Tssue Damage in Farmed Fish
  • Anette Nordby – Beyond the Pancreas: Distal Gill Filament Lesions in IPN-Positive Salmonids

16th Histopathology Report: Workshop at the 22nd International Conference on Diseases of Fish and Shellfish | Published in Bulletin of the European Association of Fish Pathologists