Most Weezer songs are no longer available since the author seems to have abandoned them all. I have compiled what I had and made it available online.
https://drive.google.com/file/d/1O8XR4mW5TPYxElmud7qFSuJISiv-_QK5/view?usp=sharing
Keep Fishin’ is part of that zip.
You are about to leave Rhythm Gaming World and access the external songs DB. While no song or file sold for commercially available videogames is hosted there and only fan generated content is allowed, Rhythm Gaming World has no direct control over the database and no files are hosted here. Alright, we had to made you aware of this, now you can visit the database!