Guest Post by Katie O’Reilly, PhD Candidate at the University of Notre Dame (@DrKatfish)
Ah, the winter holiday season. A time of sleigh bells, holly, and … fish??
As a PhD student studying Great Lakes coastal wetlands, I stumbled one day across a fish poster from Wisconsin Sea Grant that reminded me of an advent calendar – you know, the ones where you open a little door each day in December and get a treat – and thought to myself, why not instead of chocolates, you could get facts about fish? Throw in a heaping cup of raising awareness about threats to freshwater biodiversity, a dash of Great Lakes science, a sprinkling of the finest fish puns, and, voilà! A recipe for the science communication event known as #25DaysofFishmas.
I created #25DaysofFishmas on Twitter in 2016 as a lighthearted way to showcase the diversity of fish species in the North American Great Lakes. Since then, it has evolved into an annual forum where diverse audiences – scientists, anglers, residents of the Great Lakes basin and beyond – have been brought together each December to share their expertise and experiences while discussing challenges facing the Great Lakes and other freshwater ecosystems.
Each day of #25DaysofFishmas begins with the Fishmas calendar announcing the day’s fish species. It’s then followed by a series of tweets about the natural history and ecology of the species, as well as unexpected/fun facts and connections to humans.
While I joke that I created #25DaysofFishmas to combine two of my great loves – Great Lakes fish and puns – my goal was to increase awareness about species beyond the typical and familiar sportfish. To that end, some of the most popular species featured during #25DaysofFishmas have included some relatively underappreciated or unknown species; for example, the species with the most overall impressions (basically, Twitter’s measure of how many times a tweet has been seen) across all three years was the bowfin (Amia calva), a fish that sometimes has a reputation as a “trash” fish.
Because invasive species have dramatically changed the Great Lakes environment, discussions about their impacts and how to manage them are common topics during #25DaysofFishmas. Species that are not native to the basin get a “Grinch” face instead of a Santa hat on the Fishmas calendar. People often share their experiences with invasive species; for example, sharing their memories of piles of alewife washing up on Lake Michigan beaches or how they felt when zebra mussels first took over the beach at their family’s cottage. Interesting discussions about what exactly constitutes an “invasive species” have happened when featured species are not native to the Great Lakes but are beneficial to humans, like the introduced but economically-important Chinook salmon. Many people were surprised that salmon were not originally native to the Great Lakes and were introduced in the 1960s, reflecting how much the lakes have changed since the mid-20th century.
Over the last three Decembers, I’ve featured 75 different fish species found in the Great Lakes during #25DaysofFishmas. The most rewarding part of doing this outreach is seeing how engaged people get in the “shell-a-brations.” The success of #25DaysofFishmas is largely due to audience participation through sharing stories and photos, asking questions, and adding commentary.

While the original #25DaysofFishmas focuses on the Great Lakes, other scientists on Twitter have adopted the hashtag to engage audiences on different topics, with everything from a shark-themed Hanukkah spinoff (#Chondukkah), fishes of other regions (Northern California), and other aquatic organisms (#25DaysofSquidmas).
By shining a spotlight on the many diverse fish that call the Great Lakes home, I hope to inspire others to appreciate and protect the amazing underwater world of the lakes and beyond. So far, I’ve only featured about half of all the lakes’ species (75 of 178), so the tradition of #GreatLakes #25DaysofFishmas will continue for many years to come. I’m always thrilled to see new #25DaysofFishmas spin-offs, so if you’d like to try your own this year, drop me a line on Twitter!
Merry Fishmas to all, and to all a good night!