Yeah, its guaranteed that if you spend long enough fishing in that pond you will get as many of them as you want. Unlike world drop blue BoEs, which didn't used to be particularly farmable, although they might be more so now with increased drop rate in particular treasure chests.
And the wowhead posted drop rates are WAY off imo.
These are my approx stats from counting the fish in my bags after farming 4 rings.
I caught 11
Stendel's Bane - Item - World of Warcraft out of 1760 fish.
This is a .625% rate. Got 4 x
Stendel's Wedding Band - Item - World of Warcraft.
Overall drop rate for rings in my person experience = .227%
Average 440 fish to get a ring, @ approx. 15 secs per cast and catch.
Less than 2 hours to farm a ring, not bad. My guess is that everyone who says they can't get it to drop don't have the patience to sit and do the exact same thing for 2 hours.