When a dried pond is filled with water, it doesn’t take long for small fish to appear, even though no one has released fish into it. So, where do the small fish in the pond come from?
Is it true that fish eggs can exist in the soil for hundreds or even thousands of years, ready to hatch as long as there is a suitable environment?
After all, everyone knows that fundamentally all fish species cannot survive without water. However, if you have ever lived in a rural area, you would understand that the saying “where there is water, there are fish” is not without basis.
After a few heavy rains, these dry ponds have been replenished with water and revived. (Illustrative image).
In rural areas, there are often some smaller dry ponds or ditches that have been dug and then abandoned. After a few heavy rains, these ponds are replenished with water and revived. If you pass by, you may notice that there are many small fish and loaches in the pond. Clearly, no one has released fish into the pond, so where do they come from?
This raises a complex question: where do the small fish living in these ponds come from?
Rain
First and foremost, the most common and one of the most successful methods is “migration.” During the rainy season, dried ponds accumulate water, and the water does not dry up naturally. Some fish species that habitually migrate upstream may take advantage of this opportunity. After heavy rains, there is a lot of standing water on the ground that connects previously isolated ponds. Some fish that do not require high levels of dissolved oxygen in the water can overcome terrestrial obstacles and swim from one pond to another. This results in fish appearing in newly filled ponds.
Heavy rains can also bring fish to dry shallow lakes. (Illustrative image).
Transmission from Animals
The second phenomenon requires a certain amount of luck: it is due to the spread by animals. Those who frequently go to the fields may find that ponds carry other creatures, and some fish eggs may stick to them and be carried to another pond in this way.
Many aquatic birds can pick up fish eggs while drinking and resting by the pond or river. After flying away, the eggs may be transported and later dropped in a suitable resting spot. Although eggs that leave the water can only survive for a short time, there are always a few lucky eggs that can successfully settle in another pond.
Another method of animal transmission involves exclusive carp. This type of spawning can be described as “spawning and laying eggs,” where during the breeding season, carp extend their ovipositors and look for opportunities to inject eggs into the shells of clams. Clams are not stationary and often move, and they do not entirely rely on water for migration. Thanks to the clams’ “hitchhiking,” many fish eggs can successfully migrate from one pond to another to thrive.
Many aquatic birds can carry fish eggs while drinking and resting by the pond. (Illustrative image).
Bird Droppings
If the second migration method requires a certain degree of luck, then the eggs that successfully hatch in another pond through the third method are certainly the “chosen ones.” The third method is through bird droppings. Indeed, these fish eggs are “the main characters” that can survive a long time in the digestive system of birds. Many people are skeptical about this method, wondering if fish eggs can actually survive passing through the digestive tract.
A research group from Sinos Valley University once conducted an experiment: 650 killifish eggs were fed to three wild swans, and five viable killifish eggs were recovered from their droppings. Although the probability is very low, there are many types of birds in nature, and it remains a feasible possibility.
These fish eggs are ‘the main characters’ that can survive long in the digestive system of birds. (Illustrative image).
The “Rain of Fish” Phenomenon
Compared to the three aforementioned “migration methods,” the fourth method can be described as a spectacle: “airborne migration,” which, as the name suggests, is where fish fall from the sky. This occurs due to the extremely fast rotation of marine tornadoes above lakes or oceans, which can lift bodies of water and various creatures into the clouds. Under the influence of strong winds, these aquatic creatures may make a long journey before falling down, creating a “rain of fish” before our eyes. During this “rain of fish,” some fish may fall into nearby ponds.
Although this strange natural phenomenon is hard to encounter in our country, in Australia and other countries, it is not uncommon; in fact, media outlets often overlook it as it happens regularly. Some countries even hold special “rain of fish” festivals to celebrate. “Rain of crabs,” “rain of snails,” “rain of jellyfish,” and so on, have occurred all over the world.
In addition to these methods, many who have lived in rural areas may have heard explanations for the saying “where there is water, there are fish.” They refer to “thousand-year grass seeds, ten-thousand-year fish eggs,” meaning that the seeds of grass and fish have very strong survival instincts, able to revive even after thousands of years, as long as they find a suitable environment.
Putting the grass seeds aside, the saying about fish eggs seems to align with the phenomenon “where there is water, there are fish,” and it also explains why fish appear in ponds. Most fish eggs fundamentally cannot survive out of water and will not remain viable for very long. Only a very small number of fish eggs, such as those of killifish, can survive in dry environments for a limited time, but at most only for a few months. “Ten-thousand-year-old fish eggs” is merely an exaggeration, and it is also a rumor stemming from long-standing misunderstandings about scientific knowledge.
Based on these unique survival methods, it is evident that where there is water, there are fish. The “miracle” of fish is remarkable, and maintaining the balance between humans and nature must be the responsibility of all of us.
