I was at the game on Nov 15, 1969 against #9 Notre Dame, possibly the first fish tossing. Tech QB's Jack Williams and Charlie Dudish, RB Brent Cunningham and All American DT Rock Perdoni vs ND QB Joe Theisman and All American DT Mike McCoy. A great game with ND over GT 38-20. I could not tell the type of fish that pelted Coach Ara Parseghian and the Notre Dame bench from the upper east stands, but that started a fish-throwing trend at Grant field that continued at least through 2015, according to the ND fan forum
https://forum.uhnd.com/forum/index.php?action=display&forumid=6&msgid=288251&archive=1 . One ND fan stated "They were throwing fish for the derogatory name calling of Catholics, "Mackrel Snappers"." Historically, there has been no love between ND and GT fans and athletes. The football team was in the stands when we beat Coach Digger Phelp's 1972 basketball team 82-62, but no fish were thrown on the court. But we did have fish thrown at us when we played at Pittsburgh. Can you imagine how a fan's hands smelled after bring a dead fish to the game?