In both cases 'good' means satisfactory to the netsman.

Good fish, good people, either one is 'good' if they meet the criteria by which the net handler determines keeper/tosser criteria. One uses tastiness, nutrition, the other uses morality.

Now, say the guy in the office who hires the net handler says 'keep only the good fish' then one of the old hands down at the beach tells the new net handler 'compared to the salmon they serve on the Boss' table, all we catch in these nets is trash fish. There are no good fish.'
If 'good' is relative, then how can the netsmen determine which fish are good 'enough?' And how can the fish figure out whether or not they're going to be kept when they're swept up on the beach?
There's a lot of fish swimming around that are SURE they're going to be among the filleted, but really they won't really know, and shouldn't act as if they do know, until that great winnowing in the sky is performed.