For the inevitable comparisons to Ole Miss:

Actually, in 1893,
Dr. Charles Coates was recruited by LSU from the Ivy League to be the Director of the Department of Chemistry; as well as the school's first football coach, in the early 1890s.

HEEEEEEEEE chose the name "Tigers" , using the then current custom in the Northeast of naming schools' mascots after ferocious animals (Yale Bulldogs, Brown Bears, Princeton Tigers).
He even chose the initial Mascot Tiger Head and helped pick the school colors (the first game in 1883 vs Tulane was during Mardi Gras, and the only colors available in stores were purple, green and gold.)

In addition, Coates felt that purple and gold(yellow) - being complementary colors on the Artist's Color Wheel - would lend themselves very well with the image he had in mind...

Author Dan Hardesty, in a passage of one of his sports history books, related a speech Coates made at a reunion banquet given in honor of his first 1893 team, decades later.
In it, Coates put to rest the erroneous myths of his supposedly naming the team after the Louisiana Tigers - a Condederate regiment who had fought at Manassas three decades earlier.
"It was purely fiction." Coates related. "I had never even heard of that war outfit from thirty years in the past. I actually borrowed the team name from Princeton. But, rumors being what they are..."

In other words, when Coates arrived on campus, he borrowed the moniker 'Tigers' from the Ivy League. He had never heard of any war unit from 30 years prior.

Another interesting fact is that "Fighting" was not added to the name until the 1950s, in honor of a brigade of World War Ii fighter pilots from Louisiana!