Originally Posted by southamericancichlidguy23
i change the water every three weeeks and thats about it and my fish never die and there colors are bright as can be
With that many fish you will be wanting to do a water change like everyday. Probably 30%.
You should also get a test kit, your ammonia and nitrites are probably out of control.
1.) A single oscar fish needs a minimum of 55 gallons to itself. You have two in your 55 gallon tank.
2.) Your common pleco gets really big, so this already creates a problem. Also they create a lot of waste and are probably adding more to your bioload than helping out your tank.
So just with those fish your tank is already overstocked.
Not to mention the firemouth. All of these are extremelly territorial and your tank will either spiral out of control because of unstable water parameters or they will start to fight over space. They may be calmer now because they are still smallish and young. However its going to happen and my money would be on one of the oscars.
You might want to start rehoming fish soon.