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Environmental enrichment (EE) often increases positive behavioral 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 2 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 growth, brain size, and neophobic and exploratory behaviors in standard assays. Guppies given EE were bolder, regardless of timescale, although females showed a more pronounced change in behaviors than males. We further found that guppies reared with EE were smaller yet had larger relative brain sizes than guppies reared under deprived conditions. Here we highlight that EE had influenced growth, brain size, neophobic, and exploratory behaviors in guppies, and behavioral changes were observed after only 2 weeks. Our results highlight the need for assessing the influences of EE in captivity, in particular for researchers studying cognition and behavior. [ABSTRACT FROM AUTHOR]

Lake and stream habitats pose a variety of challenges to fishes due to differences in variables such as water velocity, habitat structure, prey community, and predator community. These differences can cause divergent selection on body size and/or shape. Here, we measured sex, age, length, and eight different morphological traits of the blackstripe topminnow, Fundulus notatus, from 19 lake and stream populations across four river drainages in central Illinois. Our goal was to determine whether size and shape differed consistently between lake and stream habitats across drainages. We also considered the effects of age and sex as they may affect size and morphology. We found large differences in body size of age 1 topminnows where stream fish were generally larger than lake fish. Body shape mainly varied as a function of sex. Adult male topminnows had larger morphological traits (with the exception of body width) than females, in particular longer dorsal and anal base lengths. Subtle effects of habitat were present. Stream fish had a longer dorsal fin base than lake fish. These phenotypic patterns may be the result of genetic and/or environmental variation. As these lakes are human-made, the observed differences, if genetic, would have had to occur relatively rapidly (within about 100 years). © 2013 The Linnean Society of London [ABSTRACT FROM AUTHOR]