4

We have a small pond stocked with blue gill and now catfish are appearing. How did the catfish get there if we never stocked them?

10
  • Do you know the species of catfish? Some are capable of moving across land, Could be from eggs in water plants introduced, or from someone "kindly" stocking your pond themselves.
    – bob1
    Aug 28 at 3:37
  • Are you near a body of water with catfish?
    – Willeke
    Aug 28 at 6:53
  • Second questions: how big a pond? Did you build/dug the pond yourself and stock it yourself or has it been there a while? How accessible is it for your neighbours?
    – bob1
    Aug 28 at 8:16
  • 3
    My bet would be young catfish with the original bluegill stock. Alternatively a, heavy rain event may stimulate the fish to travel. I have a small pond with many giant danios ( 3" tropical minnows). I have picked them up in the woods over 50ft from the pond after after a heavy rain; A bit surreal , walking through a weedy woods looking for fish in the grass. Roughly found 30 live ones and 10 dead ones ( many hours after rain ended.) Aug 28 at 17:19
  • 2
    Ducks can transport fish eggs on their feet or other parts of their bodies.
    – Drew
    Sep 2 at 2:39
4

How can catfish appear in our pond?

I have seen this a few times. There are basicly three primary ways for fish to end up in new ponds.

There are three primary ways for fish to end up in new ponds. The first is that they are already there. The second is that they bring themselves. The third is that someone else brings them--usually humans. The dispersal of fish into new environments follows the same rules with fish as with any other life form: fish are just a bit more limited in their transportation techniques.

Fish Are Already There

There are two main instances where a new pond forms and fish are already there. In the first case, the pond forms as part of an existing water system: a dam is made (by men or beavers or natural events), and a pond forms. Or local flooding causes lakes and rivers to overrun their shores, emptying into new valleys and low lying land, creating new ponds when the flood waters pull back. In either case, the pond forms with water already part of an existing ecosystem, complete with algae, bugs and fish.

In the second situation, the pond forms in a region that suffers regular droughts. In this case, there are sometimes local species of fish that have adapted to survive the droughts by burrowing deep into the mud of a pond while it still has water and hibernating till the next rain floods the pond and fills it with water again. They then come out of hiding to feed and reproduce, continuing their life cycle until the next dry spell.

They Bring Themselves

There are other times when a new pond forms and the fish bring themselves. If the pond forms as a result of a spring, with a steady upsurge of water, the water may eventually spill over top the surrounding land at some point and create a creek, stream or river. If the creek connects with another body of water--another stream or river, a lake or the ocean--it creates a fish highway. Fish will move into the new territory, or migrate up the stream to spawn, and will eventually find their way to the new lake and populate it.

Far less frequent in much of the world, but not unheard of is for fish with limited ability to travel over land to hike from pond to pond. Species such as walking catfish spread their territory and have invaded any number of water systems since being released outside their native territories. This method is useful only to species that survive out of water, of course.

Someone Else Brings Them

While most fish will migrate in on existing waterways, there is always a chance of transport from other sources. A pond that forms near other ponds may receive new fish from passing birds of prey dropping their catch. Similarly, fish roe that remains damp enough during a trip between ponds may wash off of the fur and feet of local animals as they move from pond to pond.

The most common species to give fish a lift to new ecological niches, including new ponds, though, is mankind. Between the new bodies of water we seed intentionally, providing new bodies of water with valued sports species such as bass and trout, and the many times we accidentally release fish or fish roe into the new water by carrying them in on the mucky bottoms of our boats and other water gear. This also includes the times when loving aquarium owners empty illegal species into open bodies of water, mankind has proven to be a major cause of fish dispersal.

So there isn't that much mystery - just logic and science to explain fish in new ponds. - How Do Fish Get Into New Ponds?

The above being stated, I have known ponds where fish have traveled from rivers into ditches, into temporary marshy grass areas and finally into ponds.

On other occasions, friends have deduced that the fish entered a pond via the eggs being attached to duck’s feet from one body of water to another. It is simply common sense.

1
  • There's also the possibility of failed predation--when they analyze bird strikes on airplanes sometimes the DNA comes back as something that can't fly. Something that could fly had grabbed it and then dropped it. Sep 8 at 3:03
2

Ducks (and other animals) can transport fish (and other aquatic) eggs (and seeds etc.) on their feet or other parts of their bodies.

This is a main way that life moves from water body to water body.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.