Fishing Spot Territories
Nearly 50% of fishing holes in the game are comprised of fish that are from two or more territory types. The combination is almost always either Rivers/Lakes or Coastlines/Deep Sea.
Fish themselves are assigned to a territory so if a fish is available in multiple holes it will still be from that territory regardless of where it is caught. As such, this is most commonly seen in ARR as that is where it is most common for a fish to be available in multiple locations.
Every hole in Mor Dhona is comprised of fish that are a mix of Rivers/Lakes, as is every non-Skies hole in Coerthas Western Highlands and nearly every hole in The Black Shroud. The majority of holes in La Noscea are either Coastlines/Deep Sea or Rivers/Lakes, depending on location. Most holes in Thanalan that are not Sands are the previous two combinations, though Crescent Cove is the only hole in the game that is comprised of three territory types: Coastlines/Deep Sea/Rivers.
A combination of Rivers/Lakes is still seen in a majority of the freshwater holes in HW.
This is still seen from SB onwards, though has continued to happen less as the contents of fishing holes have continued to become more individualised and the total amount of fish available from individual fishing holes on average has decreased.
This doesn't change much about the functionality of holes because, other than Crescent Cove, they are split into two freshwater territories or two ocean territories so the same baits are applicable.
This was most noticeable for players with Isle of Umbra Southshore. This would often become apparent because Coelacanthus was the largest Coastlines fish for nearly a decade while Endoceras from the same hole was potentially over twice as large but did not count as its territory is Deep Sea.