Looking for the same script. I got a little more information.
I have seen this on three different, unlinked, servers. On both, the plugin is called esx_fishing. I’ve asked in the ESX Discord but noone have ever heard of it.
You buy a fishing rod and lure in the esx_shops and go to the tivoli pier where there is 1-5 different blue zones where you can fish. Having a lure increases the chance of fish.
Someone else must have more information…