Host–parasite interactions in Quebec fishes: state of knowledge and emerging threats

Despite their vital role in ecosystem health and biodiversity, parasites are often overlooked or misunderstood by the public, scientists, and managers. One misconception is that parasites should be eradicated rather than studied or conserved. Thus, our understanding of many parasite species, including their impacts on hosts and ecosystems, is limited, making it difficult to predict how infection dynamics may shift in a warming world. This lack of knowledge is particularly concerning in Canadian aquatic systems, where fishes, both culturally and economically important species, are increasingly threatened. Synthesizing knowledge of host–parasite interactions in Canadian fishes can help identify areas in greater need of investigation and establish a baseline for monitoring disease dynamics over time and space. Focusing on freshwater fishes in Quebec, this perspective assesses the current state knowledge of metazoan fish parasites and highlights species and geographic locations in need of further research. We also explore how emerging threats—including climate change, invasive species, range shifts, and disease spillover—may impact host–parasite relationships. This work offers a foundation for similar studies across Canada and beyond.