Fish Tank Day

I have seen huge Koi Carp in an outdoor pool swarm to a particular point when someone walks towards them with a container. And so it is with my half dozen or so tropical fish, if I approach the tank to the right where their tub of flake food is they congregate at the top right of their Biorb.
Filter change day, the filter is changed monthly and I don’t normally forget as it is delivered so reminding me.

When the TV is off and it’s quiet the bubbling noise and hum of the filter are quite relaxing.