great tip. Though I would think any fish owner and gardener would have already stumbled upon this free source of nutes.

I have removed the filter from our 70gal goldfish tank and routinely pull the heavier, dirtier water from the bottom for foliar feeding. Dilute it with distilled water and spray away. Very beneficial.

As for not applying to produce used for consumption: Just stop using a couple weeks before harvesting and regular watering should flush the fishiness away.

As always YMMV and caveat emptor.