Methods for the collection of fish mucus: a systematic review

The aquatic environment holds a vast source of organisms that provide numerous opportunities to bioprospect new molecules. Notably, fish are producers of an epidermal mucus that offers protection against pathogens, making it a promising source of bioactive molecules. This source of molecules, however, has yet to be thoroughly explored, and particularly, optimization of methods for collection and study is needed. This review concentrates on the methods of mucus collection employed to secure high-quality samples, enabling the extraction and characterization of molecules with bioactive potential. A comprehensive search was conducted, and publications were selected based on the following criteria: (i) the mucus has been collected from the external body of the fish, not involving dissection or damage; (ii) mucus crude extracts have undergone a chemical or genetic characterization; (iii) mucus was used in bioactivity assays (e.g., antimicrobial or immune-related). Scraping, bagging, and absorption are the primary methods for collecting fish mucus. They were assessed based on fish handling, sample volume, and processing, including anesthesia and starvation. Scraping with a soft tool, such as cotton balls or sponges, proved most effective and minimized contamination, dilution, and injury risk. This review aids future studies of mucus composition and properties.