Arborwyn 5 is Grass Carp, a common fish in the rivers of Arbowyn
Arborwyn 8 is is Amberglow Tetra, a common fish in the restored waters of the Sylvaraen Roots
My geuss, is your issues stems from being too well geared, since both are lowest tiers of fish. Make sure you get rid of all sources of luck you have, and in particular unequip your Worn Medalion, in particular, if you use that.
Essentially with end-game gear and buffs, your chance of catching common fish gets very low (and probably the worn medallion makes it flat out impossible, due to it being the lowest tier of fish), due to how high you chance of getting even epic and lengedary fish are. Even uncommon fish gets hard to find with end-game gear