It's not very fun for me to have spent two years playing this game and not have a full musuem and encyclopedia yet, it stresses me out and I get frustrated spending hours fishing only to not catch these stupid fish and running around town like an idiot trying to find the rare bugs. Plus, you can trade art and fossils already
Well, I guess the game may not actually put the bugs and fish in your encyclopedia if you trade it. Or maybe they don't want people to cheat their way into getting fish. Also I think it would be unreasonable to put a fish on the ground it wouldn't breath... I guess there are other ways to do it though, but overall I think it wouldn't be a bad idea and it would help people get fish that are tough to catch like the coelacanth (which I am missing) Dang, coelacanth is hard to catch...
A fair number of them are largely up to luck, But the first time I played I really got frustrated with trying for the tarantula and scorpion.With those, at least, you can increase your chances of encountering them by getting rid of all your trees (including digging out the stumps) and flowers so that bugs that appear on or near them don't show, and then replanting after catching them.