Couldn't help but laugh when I saw the thread title.
It's nomal. Most of my tigers have been on hikari pellets for the last 12, months. When, my 12 inch IT craps, it's like a dumptruck unloading..... A redish cloud of digested pellets is expelled and released from the fish's #$s... Sometimes for up to 3-4 seconds!!
Only really notice this with the bigger tigers.