The effects of short- and long-term environmental enrichment on exploratory behaviors in Trinidadian guppies (Poecilia reticulata) Iffert, RQ and Stein, LR University of Oklahoma, Colorado State University Rq.iffert1@ou.edu Environmental enrichment (EE) often increases positive and physiological effects on captive animals. Fish are commercially and scientifically important taxa that have been shown to benefit from EE. Here we examined the effects of both short- and long-term EE in Trinidadian guppies (Poecilia reticulata). In the short-term exposure to EE, female guppies were raised in standard conditions, and after reaching adulthood were moved to either an enriched or a deprived environment for two weeks. Long-term exposure guppies were reared from birth for 12 weeks (until sexual maturity) in either an enriched or deprived environment. We then assessed neophobic and exploratory behaviors in standard assays. Our results suggest that fish given EE were more exploratory, regardless of timescales, although males showed a more pronounced change in exploratory behaviors than females. Additionally, enriched females were more exploratory than deprived across timescales, but females with long-term exposure to EE were faster to approach a novel object than those that had received only short-term exposure. EE is encouraged to improve the welfare of captive animals. Here we highlight that EE influenced neophobic and exploratory behaviors in guppies, even after only two weeks. Our results highlight the need for assessing the influences of EE in captivity, in particular for researchers interested in recreating “natural” behaviors in their laboratory studies.