Wild Tropical Fish in Snowy Canada?

by Adam Till

Although winter is usually the time when we northern aquarium keepers huddle inside and craft new aquascapes or something similarly "indoorsy", if you're brave enough to risk they cold you might just be able to do something fanatic this year.

If you venture westfrom Calgary, Alberta, Canada about an hour to the Town Of Banff, you can the see one of (if not the only) places where tropical fish live outside happily in ponds surrounded by snow!

The Canadian flag on display at the Cave and Basin

The Area

Banff is a wonderfully picturesque town in the Rocky Mountains of Alberta, and in addition to a host of other amazing places to visit, it's also home to the Banff Upper Hot Springs Cave and Basin.

A cute chipmunk at the Cave and Basin

Although the area was known to the natives of the area from time immemorial, the site was first commercialized in 1883 after a visit by Canadian Pacific Railway employees William McCardell and Frank McCabe.

A view of the interior cavern of the cave and basin

Original Photo By Kim Payant Used Under Creative Commons Attribution-Share Alike 3.0 Unported license

Conflicting claims to the area eventually forced the Canadian Government to get involved, and in 1885 an act of government carved out 10 square miles around the Cave and Basin, forming the Banff Hot Springs Reserve and creating the very first area designated under Canada's National Parks system. 

The Animals

While the historical aspects of the area might be a fun draw for Canadian history buffs, the real attraction for lovers of aquarium fish is the outfall from the springs which emerges from the hillside at roughly 27C (80F) all year round.

As a result of the perfect conditions that the inviting warm water ecosystem provides, sometime after the Second World War aquarium-loving residents of Banff decided to release a number of tropical fish species into the outfall streams.


At various times angelfish, guppies, and tetras have all been spotted in the stream and marsh areas, but the ones which seemed to take hold and thrive were Sailfin Mollies (poecilia latipinna) and jewel cichlids (hemichromis bimaculatus). In addition, Western Mosquitofish (gambusia affinis) were introduced by the government In 1924 to control mosquitoes in the area, and survive in great numbers to this day.

Sailfin molly description at the park

Whether in the 30C+ temperatures of summer or the -30C- temperatures of winter (86F or to -22F or lower, respectively), the fish can be seen year round happily eating, playing and courting in the warm, sulfurous water.

The Path

Far from being off the beaten path, getting to the Cave and Basin complex is very straightforward.

If you drive or hike through the main Banff townsite until you cross the old historic bridge over the Bow River, turning right after the bridge takes you on a direct paved road to the Cave and Basin site.

The Cave and Basin site itself features a small museum and restoration of the original hotsprings pools, and though small, the facilities may be of interest to some (the site isn't particularly extensive, but it is at least well done).

The path down to the fish is labelled the Discovery Trail, and leads north from the hotsprings courtyard.

Discovery Trail marker at the start of the site

Winding its way lazily through the old growth forrest, the path features a number of well-signed viewing platforms with nicely captioned stations describing the wildlife and folliage in the area.

Erica taking a look across the valley

Whether winter or summer, it's a fun mini-hike down the well maintained boardway!

The unique geology of the hotsprings means this is one of the few places in the world where flowers also grow year round next to the snow, and many birds, insects, and even snakes make their homes next to the warm water streams. 

Flowers bloom year-round at the site due to the warm water

As you wander down the path (be a little bit careful in winter as the wooden boardwalk can be a little slippery!), you'll get to see your first glimpses of the fish that have braved swimming up from the lower marsh regions into the upper outfall stream. The current is fairly swift, but the little mosquitofish seem up to the challenge!

Mosquitofish are in abundance in the warm spring

You'll also be treated to a fairly unique sight along the way, even to those of us jaded through years of fighting off algae in our aquariums; a rather unique white algae flourishes in the sulphur-rich water.

Strange white algae seems to find its home in the warm, sulphurous water

I could only find one reference to a legimate white algae in freshwater, but it was quoted at growing at much higher temperatures than in found in Banff, so I couldn't actually tell you much else about this unique sight.

The biology of the white algae is largely unknown

It's biology must be fascinating to grow without much of what we'd consider photosynthetic pigment!

Garter snakes live alongside the creek, and actually catch fish

When you make your way down to the marsh area at the bottom of the path, you'll be greeted by a rather unique fish watching platform, with a bird watching sibling a little further out into the marsh.

A sign showing a description of animals to be found in the area

This is where you'll be able to see most of the mollies on your journey, and even maybe a jewel cichlid or two if you're really lucky.

A description of all the fish that can be found in the pond and stream

Although we weren't able to catch sight of a jewel on any of our trips, a fellow visitor who wrote an account in 2000 did comment that they'd seen a number of the colorful fish at that time. They're likely still around, but may have moved into deeper water further away from the viewing platform.

Jewelfish are found in the waters here, but may be dying out

At any rate, the best technique for fish (and snail!) watching is to lie quietly on the platform with your head and camera peeking over the edge. You'll be able to see the fish without resorting to this up close and personal vantage, but a few moments ignominy is a small price to pay to see tropical fish in the wild I'm sure you'll agree!

Mollies in the warm stream

Not All Is Well

One of the reasons that the jewel cichlids are becoming harder to spot is that the Park Wardens are allowing the lower marsh and pond areas to silt over and fill in naturally. As a result, it won't be too long before most of the fish there will either be forced into the marsh proper (where it's likely too cold for them to overwinter), or confined to the stream itself.


Though this might seem counterintutive for an area that's devoted a fair amount of effort ot making these fish and other animals visible, it's worth pointing out again that these are introduced species, and not native to the park.

One of the markers adorning the start of the pathway

Their introduction actually forced a species that used to be native to the area to extinction, unfortunately, and provides a good lesson in how dangerous it can be to mess with the balance of nature. The marsh was actually once the only home to the Banff Longnose Dace (rhinichthys cataractae smithi), which was regrettably declared extinct in 1986 in face of competition from the introduced species.

A lesson to those that might release fish into the wild

Likewise, though the bathhouse at the Cave and Basin still stands as a reception hall and museum, the actual caves have been closed to bathers for decades (other, swimmable hot springs can be found elsewhere in Banff).


The cause of the closure was that the pools are the home of the Banff Springs Snail (physella johnsoni).

One of the endangered snails that formed the start of the Canadian park system

Original photo by Paul M. K. Gordon used under Creative Commons Attribution-Share Alike 2.5 Generic license

This unassuming little pond snail was originally found in five separate pools and their outflow streams near Sulphur Mountain; the Upper Hot Springs, Kidney Spring, Middle Springs, the Cave and Basin, Vermilion Lakes Spring, and a warm stream near the Banff Springs Hotel.

Banff National Park Mosquito fish

As a result of damage to the algae mats in the ponds in which the snails live, however, unfortunately now the snails are found only in one of the Cave and Basin springs, its outflow stream, and the Cave and Basin marsh below the spring. 

A Glimmer of Hope

Still, even in times of challenge there tend to be rays of hope when caring people choose to act.

In fact, in 1997 the Banff Springs Snail  made history in as the first mollusk to be designated as threatened. The Park takes threats to the animals very seriously as well, with numerous people being charged with relatively hefty fines when they decide to take damaging action towards the pools.

Likewise, even knowing the history of the introduced fish, it's very hard for a tropical fish lover not to be a little tickled by the sight of these fish in a snow edged pond. After all, even though the tropical fish were introduced, they actually now enjoy the full protection of the National Park, and nobody can legally catch, keep, feed, or disturb them.

Even still, although they might be only temporary denizens of the park, they're honestly a lot of fun to watch!

A Gentle Reminder

So while the marsh is a lovely place to walk on either a warm summer or snowy winter day, do keep mind of the lessons that the Banff Cave and Basin can provide.

One of the pathways leading down to the fish viewing area

Too often we hear stories of native fish being displaced by pet animals released by owners that no longer choose to care for them, and especially in areas where the released fish can survive the winter (practically anywhere for hardy fish like goldfish), the captive bred animals can cause quite a bit of destruction through disease and competition.

If you happen to find yourself in the situation where you cannot care for your fish anymore, or come across someone in a similar state, be assured that there are a number of options available to rehome unwanted fish, and options are always better than wild release.

After all, if we hope to live in a world where we can continue to enjoy nature daily, we all have to be responsible stewards of the environment.

Cheers from the snowy north!
Erica and Adam Till

Adam Till
Adam Till


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