It would be a lot easier to ban fishing from common areas by the use of a rewritten by-law. There could indeed be health and safety issues and there may also be aesthetic and ethical issues with the idea of live fish being pulled out of the water and killed and gutted, especially in front of children.
I wouldn’t pussyfoot around this. A communal swimming pool area is no place for people to be river fishing. Within reason, the owners corp has the right and responsibility to control what happens (or doesn’t) on common property.
For instance, you could theoretically pass a by-law banning the use of barbecues on balconies because of the smoke and smell that goes into other residents homes.
Check with a strata lawyer but I don’t a ban on fishing from common property would fall foul of the “unreasonable, harsh or discriminatory” test.
By the way, I was going to say that I doubted very much if there were regulations that prohibited people from fishing from shared swimming pools but then I found this NSW Government fact sheet which under “Prohibited” says you can’t “use any methods (e.g line fishing, traps, nets, bait collection) in closed areas.”
But that seems to mean areas of waters and rivers that are closed to anglers and other fishers for seasonal or stock protection reasons.