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Article History

Received: 11 April 2026

Accepted: 3 July 2026

First Online: 2 August 2026

Declarations

Competing interests: The authors declare no competing interests.

Ethics approval and consent to participate: This study did not involve original animal experimentation, as rainbow trout (Oncorhynchus mykiss) viscera and heads used as raw material were sourced exclusively from post-processed waste streams obtained from commercial fish retail markets. According to the journal’s guidelines for research involving animals ( ), the utilization of animal by-products from commercial processing facilities does not constitute primary animal experimentation requiring Institutional Animal Care and Use Committee (IACUC) or Institutional Review Board (IRB) approval, provided that: (1) the animals were euthanized prior to procurement by the researchers, (2) the tissues were obtained post-mortem as waste material, and (3) no animals were directly manipulated or sacrificed for the purpose of this research. Therefore, formal ethics approval was not required.

Euthanasia and sacrifice methods of source animals: The rainbow trout used to generate the visceral waste materials were euthanized by the commercial fish processing facility prior to our acquisition of the material. While the researchers did not directly conduct euthanasia procedures, the following standard industry practices were confirmed to have been employed by the processing facility.

Euthanasia protocol: Method : Percussive stunning (cranial concussion) followed by immediate spinal severance, a method aligned with EFSA (European Food Safety Authority) and AVMA (American Veterinary Medical Association) guidelines for humane slaughter of fish. Anesthesia : Animals were not pre-anaesthetized during commercial processing, as this is standard practice in rapid processing operations and is consistent with approved slaughter techniques. Rationale : This method ensures immediate loss of consciousness and rapid onset of death, minimizing animal suffering. The dual approach of percussive stunning and spinal severance is recognized as one of the most humane methods for large-scale aquaculture harvest. Confirmation : Tissues were confirmed to be post-mortem waste (viscera and heads) at the point of acquisition from the fish retail market, with no involvement of live animals during any phase of this research.