Photo of a shoal of Poecilia reticulata, McCauley Springs, NM.

Update on Poecilia reticulata, McCauley Spring

Photo: a shoal of Poecilia reticulata, McCauley Spring

I first wrote about this fish for my column in Tropical Fish Hobbyist, January 2013 issue ( Here’s a quote from that article about this guppy (the quote comes from my original text and may differ from the published text):

“Most everyone is familiar with Poecilia reticulata, the guppy, so I’m not going to spend much time discussing the species in general, but will provide information on the population found in McCauley Spring. I first saw this fish about a year before we moved to Santa Fe in 1991. Sometime in 1990 Susie and I took our brood to Santa Fe where Susie had gotten a job offer. We wanted to scope it out before deciding to move there. During that trip, we bought some hiking guides for the area. One guide spoke of guppies in McCauley Spring; guppies that had been there for 75 years. Checking the copyright date (1990), I wondered about a possible introduction date of 1915 for guppies. Clearly the guppies weren’t indigenous. They had to have been introduced by humans. The 1915 date seemed unlikely since that was probably the earliest guppies were kept in the US. I have diligently searched our personal library for that book, but can’t find it. The only other reference concerning the introduction of guppies into the spring I found is a 2001 paper (Ultraviolet Reflectance Patterns of Male Guppies Enhance Their Attractiveness to Females, Astrid Kodric-Brown & Sally C. Johnson, Department of Biology, University of New Mexico) stating, “The Jemez population was introduced into the spring over 30 years ago…,” making the introduction before 1970.”

By the way, I recently found a reference that said guppies came to the US in 1910, so maybe there was time enough for them to have been introduced into the Spring by 1915. Here’s a link to a very fine article about the McCauley Springs guppy:

In September 2012, I visited the Spring to collect some of these guppies. The population we now have is descended from those fish. Recently, we processed this fish. They are thriving and we’ll be releasing them for sale shortly, both adults and juveniles. The photo below shows a couple of males of this population. While most males in the population are virtually identical, these two show some variation. One has two black spots on its flank, the other one.

Photo: Male Poecilia reticulata, McCauley Springs, NM.

Male Poecilia reticulata, McCauley Springs, NM.

Good fishkeeping!