As mentionned, it's
http://ff14fish.carbuncleplushy.com/ but might look different because of night mode stuff. It's a must for fishing stuff imo, unless you keep up with it every patch. When you start and have like 300big fishes all with their unique weather and time windows, keeping track of what's up is pretty much impossible, while this lets you do just that, it's great. It also can tell you much in advance about stuff so you can prepare, like this one being 5days in advance, while most other sources are limited on weather prediction.
Anyway I've been fishing non stop for almost 2 weeks now, almost caught up. I had almost all the fishes from 2.0, but haven't really fished much since, so I had a lot to catch up. I started with all the ARR fishes and cleared that last week, this frees up a ton of inventory space since ARR has like 30baits and lures it's pretty dumb. Now I started HW and SB together since there's less fishes, but a few are just absurdly rare, or really annoying to catch(most of the fish eye stuff in HW is ridiculous).
It's fun overall though and I like seeing the log slowly fill up/the website lists getting smaller. I'm also catching a bunch of standard fishes in HW/SB since I really hadn't done much, mostly GC turn ins and leves and what not so I didn't have the fishing holes info in most zones or even the super common fishes. Up to 705unique fishes and 138big fishes atm, so progressing at a pretty rapid pace.