The triumph reads "catch fish while a fish pond is at its maximum catch bonus"
I have spent almost 6 hours testing this. No matter what I do, the triumph will not progress. I have been at max and caught each type of fish while at the max catch bonus and im stuck at 0/25. I dont mind the grind but a triumph like this should just work. It also doesnt help when the Public Events just spawn in and remove the fishing bonus. I know the work around of leaving fish on the ground etc. Trst me, I have tried everything. Please Fix :)
Triumphs in general are bugged, including the ones for fishing.
I have caught 488 fish. There were many Legendary fish in those 488. The Gotta Hook'Em All triumph stopped progressing when I had caught 6 Legendary fish.
Similarly, The Spend Salvage Keys triumph shows zero keys spent even though I have spent many keys.
These are just a couple examples. There are several other triumphs that have bugs, too.