I'm relatively new to tropical fish (2 months into it) after switching from goldfish keeping (aka a never-ending fight against poop and ammonia). My goldfish constantly sifted through the substrate looking for something to eat and begged at the top of the tank whenever anybody approached. I am just wondering (and I hope this is not a silly question): is the same true with tropical fish (mollies and platys in my case), or if I see them searching for extra food, are they actually hungry?