My fish have always done this after a good water change. Must mean they are content. I actually like when my silver dollars do this. I mean fish swim if they are just sitting in a corner must mean nitrates are high or they are sick. Take all the water out of the tank and they will stop doing this. LOL
I take those extra parts I never use for pumps and stuff. You know the plastic pieces... I toss them in the tank. I have this one [FONT=Verdana, Arial, Helvetica, sans-serif]Tropheus Duboisi[/FONT] it drives him crazy. Always moving them. The Oscar just attackes new things and does the face off on the divider.... His name is Nemesis loves to face the glass. Can care less for the snails.
Maybe spend more time near the tank without feeding them. They associate your presence with food, so maybe if they see you near the tank more often without being fed, they'll calm down.