I did some more research and it looks like it was a Skipjack herring.

Funny, but the picture doesn't look as much like a tarpon as I
remembered it. I know they were great jumpers when you caught one of
the little rascals.

It was on the Pearl river below the dam, so I guess they would come up
river and get stuck at the dam and stay for a week or so and then
disappear. You might not see them again for a long time.

wrote:
The smallmouth love to congregate up and chase yellow tails,(skipjack), in
the current down here....

We used to catch a small fish that looked like a baby tarpon and we
called it a skipjack. We used them for cut bait to fish for catfish.
They seemed to just show up for awhile and then you might not catch any
for a year. I don't remember the time of the the year, but I am pretty
sure it was summer. You could talke a small bait like a beetle spin
and run it real fast near the top of the water to catch them. They
wouldn't be over 8-10" and looked and jumped just like a tarpon. Funny
you should mention that, I haven't seen one in many years.