enough

  • We are currently upgrading MFK. thanks! -neo
1 oscar 2 green terrors 2 demps 1 pleco
11-12 inches 3 to 4 inckes 5 to 6 inches 13 inches

water is always crystal clear i do a water change every 4 months params are perfect
 
Your filtration is fine,but all those big,territorial,aggressive fish in 72 gallons! I would get rid off all of them but your oscar.

You should also be doing water changes every week.I bet your nitrate is off the chart after 2 weeks,let alone 4 months.
 
It's very overstocked,and when they all mature,aggression will become an issue in such a small tank,because they are fish that like to establish territories.
What kind of test kit are you using? Do you have live plants?
 
nitrates should be less than 40ppm, not 400ppm.

Seriously, what are your exact parameters, because 4 months with no water changes on an overstocked 72g usually doesn't equal clear water and perfect parameters. If it does, you've discovered something and need to share.
 
MonsterFishKeepers.com