Is there such a thing as healthy fear?

You need to define fear, here.

Foresight, which comes with a little emotional punch in response to what is foreseen, is obviously necessary for good decision-making.

Prudence, caution, and preparation flowing from such foresight are therefore desirable, too.

Fear, which might be defined for these purposes as the emotional state arising from dwelling to no purpose on prospective negative events or situations, is essentially delusional. One is constructing mental scenarios that are not (yet) real, then feeling emotions associated with events that have not happened.

This need not be.