Back in tha day my first fishwas an Oscar in a 25 gallon...' lots of room for life' I was told at lfs as a teen. This was before google, youtube etc. and Oscar books gave me average info on how big to house a pair. well my friend, his head, forehead rather looked chromagnum and died at 5 years old ;( I had no fishfriends so none the wiser that what I was doing was wrong or cruel. As for over filtration, this is a misconception as it has nothing to do with over filtration being okay for overstocked fish but surface area for gas exchange, waterchanges and horomones etc...elements that overfiltering will do absolutely nothing for those critical issues.