Ghost Whale Shark enlargens the grid of the tank

When I put a ghost whale shark in a tank, it enlargens the grid.
I also can’t put the tank with the fish in a room that’s otherwise big enough (not even with ALT).
Only when I first place the tank and then put the fish in, but then I can’t move the tank anymore.
It doesn’t happen with the common Whale Shark or the Orca.
Didn’t test the other fish for this tank yet.
No mods here.

where did you end up catching the whale shark at? orca?