Turtles Can Live in Peace with Goldfish
(With waterlilies too?)

by Peter Kacalanos, Director,
Geneva Area Pond Club & Geneva Area Turtle and Tortoise Society
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The waterlily ponds in our garden here in Switzerland are teeming with life. The dozen goldfish we started with turned out to be exceptionally promiscuous, and soon populated the ponds with hundreds of their progeny. We later added aquatic turtles to the ponds, and now they live in perfect harmony with the fish. The various warring factions in the Middle East could learn a valuable lesson from our animals’ peaceful coexistence.

Many members of our pond club and our turtle society had advised us not to tempt turtles with presumably delicious goldfish. But we felt it was worth seeing if they could peaceably share a home, and we’re pleased to confirm they can. We learned of their compatibility with a little experiment:

I knew that most animals are territorial, and feel safe in their own little part of the environment. Assertive interlopers might want to move into that environment, but most do so quite cautiously if it’s already inhabited. As a general rule, in nature the animals that are already in a territory tend to keep it, while those planning to move into the territory usually decide to coexist with those who came before.

With that in mind, I set up an experiment in our 500-liter (over 125-gallon) aquarium. I stocked it with very many aquatic plants on both ends and the back wall, leaving the front central area free for open water. I added a dozen young goldfish from our ponds, and they seemed to enjoy swimming through the dense vegetation as well as the center stage. After a month, when I was confident they were familiar with every nook and cranny in the jungle of water plants, I decided to test my theory of turtle-fish compatibility.

I fed one young turtle till it was sated, placed it in the aquarium, and watched to see what happened. Some fish seemed unconcerned, while others exercised their discretion by deciding that this was a nice time to stroll through the jungle. In short order all the fish were swimming around the turtle, examining it without fear. Days later the turtle seemed to notice the fish for the first time, and half-heartedly snapped at a few that came near its mouth. But the fish were already familiar with all the hiding places among the plants, and retreated to their safety whenever they sensed danger. The turtle seemed to acknowledge the fact that the fish were living in that environment first, so it accepted its position as the new kid on the block. All the fish and the turtle were soon eating the same goldfish food at the same time. The turtle seemed to prefer casually dining at the feeding ring instead of exerting itself by chasing down a fish to eat.

In each of the next three weeks I added another well-fed young turtle to the aquarium, until there were four turtles sharing living quarters in harmony with the dozen goldfish. Just like the latest family to move into an established community, the new turtles seemed reluctant to antagonize their piscatorial neighbors. Well, I did notice one tiny nip taken from the tail of two of the fish, but the missing parts regenerated themselves within two weeks.

When club meetings were held in our home, members of the pond club and the turtle society were surprised to see the fish and turtles living together so peacefully. Everyone remarked on how graceful the turtles were when seen swimming in the aquarium, in contrast to their lumbering gait when walking on land. (A ramp in the aquarium led up to a dry basking platform warmed by a sun lamp.) It was also a pleasure to see all the beautiful markings on the turtles’ skin and shells from just inches away, an appreciation not available when viewing turtles in the wild.


Over time we watched the turtles grow along with the fish, and noted happily each time we counted that there were still twelve fish, intact with all their appendages. Three months later I was finally satisfied that no major damage would befall the goldfish living in our garden ponds, so I transferred the four turtles from the aquarium into the ponds.
They must have reveled in their spacious new 29,000-liter (over 7,000-gallon) home with its profuse variety of aquatic plants and lots of underwater caves to explore. They swam all over, and found many logs and rocks along the banks on which they sunbathed for hours at a time. I had designed our ponds to look as natural as possible. The turtles basking on the shores heightened the impression that the wildlife ponds were always here, and that our home was later built beside them. 
The turtles soon learned to come to the goldfishes’ feeding table in the ponds whenever I fed the fish. Our fish eat a wide variety of comestibles besides commercial goldfish food. Their favorites are canned or dry cat food, hard-boiled egg, cooked or raw rice, cooked pasta, raw oatmeal, wheat germ, bread, corn flakes and virtually any other kind of cereal. Luckily the turtles eat the same foods, so they’re always well fed. (We wouldn’t want them to go hungry among our goldfish.) We haven’t yet seen any turtle chasing or eating any of the fish, although we could certainly spare some among the many hundreds there. As aquatic turtles mature, they develop a more vegetarian diet. Ours will soon be nibbling on some of the more tender plants growing underwater. That’s fine with me, because I won’t need to remove the excess vegetation from the ponds as frequently.




Turtle club members saw the natural environment in which our turtles were thriving, and described it to some friends who were confining their turtles in small aquariums. Three of those friends each gave us their pet turtle, so we added them to the four already living in our ponds, for a total population of seven as of this writing. We might have more this spring, because we’ve found several holes dug into the soil around the ponds. They looked exactly like the test-holes female turtles dig before they find the ideal place to lay their eggs. We didn’t find any eggs, but there might be some hidden in a covered nest, and baby turtles could hatch out this spring. 

Other water gardeners might enjoy the sight of one or more turtles swimming and basking in their ponds. We assume our experiment shows that well-fed turtles can live in peace with pond fish. We also assume they can be introduced directly into a pond where fish already know all the hiding places, as we did with our latest three turtles. That obviates the need for a preliminary trial period in an aquarium. There are no guarantees in life, so a skeptical ponder should ponder the likelihood of any negative possibilities before acquiring turtles for the pond.

We certainly counsel against choosing aggressive species like snapping turtles, musk turtles, mud turtles, or soft-shelled turtles, and all pond fish would certainly concur. (Those turtles also spend almost all their time on or in the mud at the bottom of a pond, so they’d rarely be seen and admired.) All of our turtles are of the species Trachemys scripta elegans, called Florida turtles in Europe, and red-eared sliders in the US. Other turtles in the genera Trachemys, Pseudemys, Chrysemys, Graptemys, and Clemmys have similar habits, so they would also be good choices for ponds. They’re varieties commonly called sliders or cooters or painted turtles or map turtles or pond turtles. Many are readily available in the larger pet shops, and can be ordered from breeders with Internet web sites.

Bear in mind that each individual turtle has its own personality. We were charmed to see the distinct differences, both when ours were in the aquarium, and in the ponds now that they’re mature. We do miss the ability to watch them up-close in the aquarium. That’s also where we enjoyed watching the courtship rituals between a male and his chosen paramour. Most male aquatic turtles can be recognized by the very long toenails on their front feet. To impress a female, the male swims backwards before her and vibrates his nails very quickly right in front of her face. It’s almost a blur, and occasionally the nails even caress the female’s face. This display seems to have a salutary effect on the female, and she soon allows him to mount her from behind.

That’s when we see the reason for the differences in the other secondary sexual characteristics of males and females. The female’s plastron (the lower shell) is slightly convex to make room for the eggs she’ll develop within her body. The male’s plastron is slightly concave instead, to facilitate mounting on the female’s carapace (the upper shell). His tail is also fatter and longer, so that it can reach around under the female to accomplish fertilization. The cloacal opening on the female’s tail is close to the base, but on the male’s tail it’s closer to the tip for the same reason. The mating takes place under water, but the female has to climb out on land to dig a hole in which to lay her eggs.

She chooses soil that she can dig into easily with her hind legs, then covers the hole with soil again when she finishes laying. Water gardeners with turtles should provide a suitable nesting site in a sunny area near the pond, because it’s the heat of the sun that hatches the eggs. Turtles usually lay two clutches of eggs per year. Eggs laid in early spring will hatch in the summer; eggs laid in late summer will hatch the following spring.

When WGI asked Peter about turtle damage to waterlilies, he replied:

Good Turtle! Bad Turtle!

Our turtles treat our waterlilies with respect. Our turtles don't run or yell in the house. Our turtles dress like young ladies and gentlemen. Like children raised properly in a good home, our turtles behave in a dignified manner, as befits their upbringing.

We've heard that other families' turtles eat their water lilies, but we haven't yet experienced such unacceptable behavior. It might be another manifestation of each turtle's distinct personality. Maybe we were just lucky in getting turtles that don't like the taste of waterlilies--at least the taste of our waterlilies. They must prefer the soft tissues of the jungle of underwater plants in our ponds, plus the wide variety of foods they share with our goldfish. We haven't performed a taste-test ourselves to see which tastes better, but you're welcome to do so yourself and then present your report. If other ponders want to get rid of their turtles, we'll gladly give them (the turtles!) a good home here in Switzerland.

In our garden we keep terrestrial tortoises as well as aquatic turtles, and we always dig up their eggs and place them in our homemade incubator for hatching. We regulate the temperature and humidity in the incubator, both to maximize the number of healthy hatchlings, and to influence the percentage of males and females. Slightly higher temperatures tend to produce more females for our breeding colony.

Our seven turtles and eight tortoises have the freedom to stroll over our entire garden. They can’t wander any farther, because I’ve installed meter-high fencing completely around the garden. The bottom of the fence is buried six inches deep, further assuring that the turtles and tortoises stay in and any potential predators stay out. Others with gardens too large to enclose completely may choose instead to install fencing just around the pond itself. Two or three feet of land area around the perimeter of the pond should lie within the enclosure.

Now that it’s November, our turtles and tortoises are shifting into hibernation mode. The land tortoises have been spending cool nights in their insulated shelters, and will soon move in to sleep there like bears until warm weather returns in spring. The water turtles will spend the winter buried in the mud at the bottom of the ponds, the warmest area of the water garden. None of them will need any food or other care until they wake from hibernation in spring, so we always take our long vacations in the winter.

Everyone planning to add one or more turtles to their ponds should first acquire some books about their care from the library or pet shop. Until then, they can find lots of information on our Geneva Area Turtle and Tortoise Society’s web site at www.turtles.meetup.com/44. It includes over 200 captioned photos of turtles and tortoises to help identify the various species, complete alphabetical lists of every species and subspecies known to science by scientific name and by common names, links to 600 other turtle and tortoise web sites on the Internet, a description of our effective turtle-egg incubator, and much more for everyone interested in keeping turtles. All water gardeners can instantly join the turtle society for free right on the web site, wherever they live, and attend its free meetings whenever they’re in the Geneva area. They can also join our Geneva Area Pond Club for free on its web site at www.ponds.meetup.com/1, where they’ll find tons of information about water gardening. And whenever they’re in this part of the world, they’re welcome to visit our ponds to see how easily turtles and goldfish can live in harmony.

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