I'm right there with ya.
Just started on Saturday and I've already caught every fish possible that's accessible in June (both in my village and the island).
Hoping to clear out the rest of the wetsuit deep dive critters on the Island tonight (will be a while until I get to do the same for my village).
That'll just leave the pesky bugs. Went on a beetle smorgasbord in the evening. Have a few daytime-only stragglers to clear up as well. Will be waiting on a few for a while, though. Don't have an axe to get violin beetles in my village. Going to let some turnips rot to get ants and flies. Trying to get my hybrids off the ground to get a Peacock Butterfly (still working on the Orchid Mantis as well, although they'll go for white flowers). Need a bush for snails. And still have to nab that pesky tarantula. Only seen him twice, thus far.
Pretty much covered on everything else, though. Anything that isn't situational will be mine in the next day or so.
Museum has always been my favorite part of this game. In my town before it got wiped out, I had a ton of fossils and bugs. Those are mainly the two things I love collecting, fish are a bit too random for my taste. You can always see what bug you'll get before you go after it. As for fossils, I love the building aspect. Seeing the skeletons slowly get put together is awesome. Now, I get to do that all over again I guess, haha.