Raining fish bring life to ponds

I HAVE made a number of garden ponds in my life and, because I’m interested in such things, I’ve always kept a close eye on the plants and animals that colonise them.

It’s remarkable how rapidly life appears in a new pond. In most cases there are logical explanations for how it gets there. Many pond insects, like water beetles and water boatmen, can fly. They don’t do it very often but, often once a year and often at night, they reveal their wings and fly off in search of a new body of water to colonise.

Then if you collect anything from a wild pond — perhaps oxygenating water weeds or frog spawn, you may inadvertently introduce other animals, or at least their eggs or tiny larvae. There is also a theory that water birds transfer fragments of weed, sometimes with eggs attached, when it gets tangled in their legs — though most of the ponds I’ve built have been too small to attract water birds.