Anyone else have toilet trained fish?

[Hross]

My half black mimic tang does the same. Also front left corner

 

[Orion9]

My Caribbean blue tang knows when my Gem is about to poop, they both head to the left front corner, Gem poops, and the Caribbean eats it....

 

[Troylee]

My white tail bristle tooth does the exact same thing! Haha