LOOKING FOR A BL MANGA!!!!!!! URGENT

OKAY. I don't remember that much anymore because I've read it in 2021 but. What I remember was a guy working at a university (??? I'm not sure but he was some kind of a teacher) and was a marine biologist. There was a plot that he was made fun of because of his interest in the marine life blahblahblah and the guy he fell in love with was a blonde delivery guy younger than him. The fish guy had a black turtleneck as his main look I don't know why I remember this so vividly but I did so. Also I have NO IDEA if it's on mangago I read it on some now defunct site but if any of you even Suspect that you know what I'm talking about please reach out to me. Please it's been 60 years