My fish, like many others, seem to love getting into tight places. In this case, I had doubled up the panel in a spot where the two fish liked to flare at each other hoping to reduce that just a bit.
Turns out that Red just wanted to get between the panels, going through the “Tunnel of Doom” over and over again.
Don’t worry, Red was always safe, and was able to leave on his own. And after I removed the double panel, he found plenty of other places to get into.