I was amused to see this review of the history of zebrafish publications. It describes some of the trends in the research (read: lots of developmental biology), and plots the number of papers published. I started working with zebrafish in 1979, so I’ve marked where I began.
You know, when I started out as a grad student in this field, the literature search was pretty easy. Almost all the people who had published on this model system were right there in this one collection of labs at the University of Oregon, with a few other former students scattered elsewhere, so I could just turn to all of the primary authors and ask them directly about anything. There were a few older papers, but as I recall, almost all of them had to do with zebrafish as guinea pigs in environmental toxicology studies.
It’s a little bit different now.
(Of course, that didn’t mean I didn’t have lots to read — the questions were all focused on neurobiological and developmental topics in other organisms. Even now you shouldn’t center your reading on just one experimental animal!)