Pejerrey (Odontesthes bonariensis) Under Siege: Main Infectious Diseases and Their Role in Aquaculture and Wild Populations Amidst Environmental Change.

The pejerrey (Odontesthes bonariensis) is a key species for recreational and commercial fisheries in Argentina and holds significant aquaculture potential. It has been introduced to various countries worldwide, including Japan, where intensive aquaculture has developed. However, infectious diseases present major challenges to its cultivation, as pejerrey is susceptible to diverse pathogens, including bacteria, fungi and parasites. The primary bacterial pathogens affecting pejerrey include the genera Aeromonas, Pseudomonas and Mycobacterium (M. piscida). Fungal-like pathogens such as Saprolegnia spp., and fungal pathogens such as Achyla racemosa and Fusarium species (F. solani and F. semitectum) are also prevalent. Additionally, pejerrey hosts external and internal parasites, primarily Lernaea cyprinacea and members of the genera Cangatiella, Gyrodactylus, Contracaecum and Diplostomum. This review explores the primary infectious diseases affecting pejerrey, focusing on their symptoms, epidemiology and causative pathogens, based on literature from multiple countries and languages. Although no new diseases have emerged, we have identified persistent challenges that have remained unsolved for decades, highlighting the need for further research. Understanding the biology and epidemiology of these pathogens is crucial for expanding the aquaculture of pejerrey. Moreover, we examine how environmental changes, such as global warming, pollution and alien species, may influence disease dynamics in wild populations, stressing the need for management measures to preserve this valuable resource.