Now and then, a new pond appears in an area where there was previously no water. And, out of nowhere, fish appear and flourish. But how do fish tend to appear out of nowhere in ponds? Is it a sleight of hand? Did the fish appear from nowhere? Did they appear out of thin air?
Fish can enter a new pond in one of three ways. They could have been there before the pond developed, they could have swum in from another body of water, or they could have been transported by other animals or even yourself!
It was believed that water birds move fish eggs into these waters for decades. But a systematic literature review conducted by researchers at the University of Basel found no proof of this to date.
The bulk of global freshwater habitats is small lakes with a surface area of fewer than 100 m2. Many of these lakes are in remote, mountainous areas where there is no inflow or outflow. Nonetheless, fishes are in the majority of these bodies of water. So, how do fish get to lakes and rivers that are isolated from other bodies of water?
Some of the most prominent natural scientists of the nineteenth century, such as Charles Darwin, Alfred Russel Wallace, and Charles Lyell, had already considered this question and came to the same conclusion: water birds must be responsible for fish dispersal.
And they had a good reason for it, some fish eggs are sticky and can last for a long time out of the water. The fish eggs adhere to the feathers or feet of water birds, which then fly from one body of water to the next, where the fish hatch from their eggs.
Some of the fishes found in ponds are pumpkin seed fish, high fin banded sharks, red shiners, mollies, guppies, weather loach, siamese algae eaters, plecos, Pond Sturgeon, goldfish, golden orfe, and koi carp.
Here are the three ways by which fish can enter a new pond.
Getting the Fish into Ponds
1. They Were Already There.
The first time fish end up in a pond is if they were already there when it was formed. It can occur in one of two forms.
First, the pond may have developed as a result of an existing water source being disconnected from the main water supply. It may be due to a dam, natural disasters such as an earthquake or landslides, or animals.
Flooding can cause the water level of a river or lake to rise and spill over its banks. When the water levels recede, the water empties into low-lying lands or valleys, leaving a pond.
When this occurs, the pond water already contains all of the necessary materials and organisms for a complete ecosystem, including fish or spawns, bugs, algae, and plants.
When a pond grows in an area where there are frequent droughts, the second phase is possible. Local fish species can adapt behaviors and characteristics to help them survive the dry season as a result of this situation.
It involves the ability to burrow deep into the mud at the pond’s bottom. Then, before the next rainy season, when the pond refills, they go into hibernation.
When the water returns, the fish emerge from their hibernating and secret state to feed, mate, and reproduce, allowing them to continue their life cycle before the next drought. Indeed, fish aren’t the only ones who can do it.
Other marine species, plants, and insects may also survive a dry spell by surviving in a near-dead state. Some aquatic animals lay drought-resistant eggs that hatch when they detect water or moisture nearby.
2. They Swam Their Way Into The Pond.
Another way to address the issue is, How do fish get into ponds? is that they swim there and then naturally deliver themselves.
For example, a piece of land is designed in such a way that a drainage system connects various bodies of water and enables them to share a water supply, including their inhabitants.
A steady supply of water, especially when a pond or lake is created by a natural spring, can raise the water level.
Rising water levels in a lake can cause it to overflow and flow to a low-lying area through creeks, rivers, and small streams. It could result in a new body of water in which other marine animals and fish could swim.
The water rivulets serve as a highway between the main lake and the newly created pond or lake. And, after the water levels return to normal, some fish find their way to the new body of water and remain and breed there.
A brief duration of flooding may often wash fish from neighboring bodies of water into a specific pond, river, or lake. Another uncommon but not unheard-of phenomenon is the tendency of certain fish species to migrate from pond to pond over land or mud.
By rolling on its fins, the walking catfish, for example, expands its territory and invades other water systems. Lungfish and other animals can leap short distances.
3. They Were Transported.
Finally, fish can be transported by accident, either by nature, other species, or even by you. In this way, a majority of fish and marine animals get to newly created bodies of water.
The migration of fish with the assistance of land animals, birds, and humans is another, possibly the most exciting of all. A pond near another lake or pond can receive fish from birds of prey that fly over it and drop their catch by accident.
Fish eggs or roe can also wash off and hatch in another pond from the feathers, paws, or fur of animals that wander between ponds if kept moist during the journey. Some birds, such as pelicans, or other animals can carry these eggs or juvenile fish in their mouths.
Humans are the most common species that move fish from one location to another, although unwittingly. It includes aquarium owners who release aquarium species into the wild without permission.
We intentionally release fish and eggs, particularly game species like trout and bass. On the other hand, some of them end up in water bodies by sticking to our water gear or the bottoms of our vessels.
They may also cling to algae or aquatic plants that you introduce to your pond and become stuck.
How Big Should A Fish Pond Be?
Ponds are found in different shapes and sizes, ranging from small and plain to broad and complex. The more water in a bath, the more stable the biology and temperature of the water would be. Stable temperatures aid in the regulation of the pond’s environment, keeping algae at bay and fish and plants satisfied.
Even if you only have a small amount of space for a pond, increasing its depth will significantly increase its volume. Increasing the depth of a pond from 24” to 36” would raise the amount of water by 50%.
We suggest that a typical ecosystem pond be at least 24” deep, with a few shallower areas/shelves for plants. If you want to keep some fish in your pond (such as goldfish), 24” is the absolute minimum size.
Deeper water often helps the fish to escape predators if necessary, so having a section of the pond that is deeper than the rest can be beneficial. For example, at one end of the pond, you might have a shallow layer, then a second level that drops to 24” deep, and a third level that drops to 36”.
Bear in mind that the more water volume you have, the larger the skimmer, pump, and filter would need to be, requiring more energy to operate. Pumping the entire contents of a pond every hour or so is a reasonable rule of thumb.
So, for a 1000-gallon pond, a pumping system that runs at around 1000 gph is needed (gallons per hour). Pumping requirements increase to 2000 gph if the water volume is increased to 2000 gallons.
So now you know the three ways fish could end up in your pond, they could have been there even before it was created, they could have swum in from somewhere else, or they could have been transported.
The preservation of biodiversity necessitates an understanding of how fish spread in remote bodies of water. The knowledge of how species colonize new ecosystems is essential for the protection of refugees and selective reintroduction. It also helps in the prevention of invasive species spread.
There is no mystery here, and no magic or aliens are involved. Mother Nature only shows that no matter how hard or unpredictable life can be, it still finds a way.