Goldfish Change of Behaviour

by Linda
(Reading UK)

For the previous few years our goldfish in our pond surfaced around the same time each day and waited to be fed.

During the summer the goldfish suddenly did not emerge in our pond. After a few weeks some started being visible. They fed from the surface but did not stay as in the past. Have they had a shock? Today they did not emerge at all.

Any advice please?
Thank you

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Grant’s Reply

Hi Linda
There are a few reasons Goldfish will suddenly change behaviour, especially at feeding time which is one of their primary behaviour drivers.

Two of the most common are sickness and the presence of a predator.

Sickness suppresses appetite, but usually, Goldfish have to be pretty sick not to appear at feeding time. Over this period of time you should have seen evidence of sickness with some deaths.

I suspect there is either a predator, one that emerges at night, or a fish eating bird such as a Heron visiting the pond.

With their bright colours and tameness, Goldfish are an easy target.

Do the fish numbers appear smaller, and if so is it the smaller or larger fish that seem to be missing?

Smaller fish disappearing suggests a bird such as a kingfisher is in the area or a fish eating amphibian is in the pond. Bigger fish disappearing suggests a cat or heron.

In the South East of Britain, otters have become a problem, cleaning out ponds of large expensive fish very quickly.

If your pond isn’t covered I would suggest it will need to be going forward as the predator isn’t going to stop visiting the pond until all the fish have been caught.