Goldfish Chasing.

Question
Hi, I'm a new goldfish keeper, and haven't been experiencing any problems with my goldfish except for a curious notification.
I've gotten all of my goldfish from a good friend of my brother. I currently have 7 and they're all under 1 inch except for the biggest one; its a little over an inch. They all live in a 10 gallon tank with proper filtration and food all made from Tetra. I change the water in the tank and wash the gravel and change the filter about once a month so I believe everything is fine.
The thing I've been noticing is that the biggest goldfish always chases the smaller ones regardless if of its size. The other goldfish don't chase each other at all I've read from online articles that these are signs of breeding, but I'm not quite sure if these goldfish are doing that because they are really small and usually the goldfish being chased is trying to escape the biggest one.
So is this common fish playing or is it breeding or what?

Answer
Hi Benjamin,
It's probably not breeding, but it may just be the pecking order like almost all fish have. Even peaceful schooling fish have a pecking order and occasionally behave somewhat aggressive in chasing or even nipping their own species. It's no big deal and a natural behavior. Which is likely what is happening with the goldfish. Just make sure the smallest goldfish isn't being made miserable which could be another reason why they are being chased, because they are the smallest and highest ranking goldfish in the group.
Be sure to be ready to upgrade your aquarium soon (you may already know this but its worth mentioning) 7 goldfish in a 10-gallon won't work out well for very long.

I really hope this helps!
Best of luck,
Karen~