'Tis good fish if it were but caught.

Understand the thought

Meaning in plain English

An attractive possibility is not yet an achieved result. The good fish still needing to be caught distinguishes what might be valuable from what is actually available to use.

What the words are saying

The fish can be judged desirable in the image, yet its value remains conditional on catching it. Figuratively, a promising idea or offer may need practical steps before it supplies the benefit being discussed. A useful reading names those steps and checks whether they are feasible. The saying does not make planning worthless, nor guarantee that every promising opportunity should be pursued. Some possibilities remain unsuitable after examination. Its emphasis is the gap between imagining a useful result and securing it, rather than a judgement about fishing methods or a demand to claim success before the necessary work is done.

Everyday example

A group discusses a useful guest speaker but waits for confirmed availability and an agreed venue before advertising the session as arranged.

When to use it

Use it when a promising possibility is being counted as an accomplished result.

Agent-assisted editorial interpretation. This explains the words; it does not by itself verify their author or earliest origin.