Poecilia reticulata as a Model for Monitoring Endocrine Disruption in Aquatic Environments: From Biological Responses to Sustainable Water-Quality Assessment

This narrative review evaluates the multi-scalar ecotoxicological capacity of the guppy (Poecilia reticulata) as an integrative model organism for monitoring endocrine-disrupting chemicals and establishing sustainable water-quality assessment protocols. By virtue of its distinct biological attributes, including vivid sexual dimorphism, viviparous reproduction, and a thoroughly mapped behavioral repertoire, this teleost species uniquely bridges the interpretive gap between sub-organismal molecular changes and broad individual reproductive fitness. The synthesized evidence demonstrates that diverse contaminant classes, ranging from legacy steroidal estrogens and antiandrogenic pesticides to industrial organotins and emerging per- and polyfluoroalkyl substances (PFAS), provoke mechanism-specific toxicities that disrupt hepatic vitellogenin production and neuroendocrine brain aromatase pathways. These physiological initiating events directly propagate into diminished sperm motility, degraded secondary sexual ornamentation, altered courtship tactics, and distorted population sex ratios. Furthermore, this review addresses the applied utility of P. reticulata bioassays in measuring the net ecological hazards of complex industrial wastewaters and chemical mixtures. Ultimately, the work situates the guppy within modernized, tiered environmental monitoring frameworks that pair targeted chemical profiling with animal-sparing New Approach Methodologies (NAMs), thereby reinforcing resource-efficient and ethically sustainable strategies for protective global water management.