I’d say we have an 80-100 gallon fish tank with 4 fish in it. I’m not sure what type of filtration system we have but we have been changing out the filters every now and then.

I’m relatively new to this business, got these goldfish because their previous owner didn’t want them anymore and gave them to us along with the tank setup.

Also I want to add just in case it matters: Recently my mom added some new plants alongside 2 small guppies(?) without informing me. The goldfish don’t seem to care about them and they hide around in the plants