Urmetz, you seem to be positive that fish eggs transfer by other creature, animal, or bird and thus stock other bodies of water. How can you be sure when there is so much evidence to contrary, some of this evidence having been presented above?
We all can have our opinions, but the only confirmed way to get hitchhikers into your pond is by intentional stocking. Either a friendly individual trying to do a favor and bucket stocking, or by you unintentionally putting them in with wanted stocker fish as Bobby shows above. These can be confirmed because they can be witnessed and proven.
If you believe strongly that kingfishers carried them to you and dropped them in, or that a fish eating bird happened to burp them in the pond at the right time, then that leads you to many more hard to grasp and hard to prove theories such as the eggs made it through the GI tract of a passing eagle and somehow hatched, or that eggs were really toad eggs but evolved into gambusia.
There always is healthy debate about this topic and I think that debate should continue, but until we can really observe the event happening, we really shouldn't insist that a ridiculous explanation has to be the correct one.
I'll be the first to say that we don't understand all there is to know about nature and how it works. I'm sure if I lived in the days when the earth was 'known' to be flat I would have wondered if that was true too. But until someone observed it to be round, they simply just didn't know...
You never can be too careful when stocking tiny fish and a thorough sorting is a must.
Fish are not dispersed by being dropped into a body of water, except for those intentionally dropped by airplane into remote bodies of water as part of a fish stocking program.
