You know that "pleco" is a term refering to about 500 different suckermouth catfish right?

If its the cheap common pleco it will need at very least 75 gallons, possibly much much more as they can reach 2 ft.

Smaller kinds like zebra pleco (which max around 8 inches) will need around 30+ gal.

The oscar all alone should have 75 gallons as they often grow longer than the 55 gal is wide...

• How much gallons of water does a one inch pleco algea eating fish need?
• What is the best kind of algea eater to get for a fish tank?
• When fishing for salmon are you allowed to clean the fish of the fish eggs then throw fish back in water?
• Bought 4 discus fish two different fish store two are eating and the other two is not but they look healthy ?
• How many gallons of water are in the ocean?
• Changing water in Betta fish tank: Dechlorinating the water and transferring the Betta fish?
• My fish ent eating fish flakes?
• Is the "1 inch of fish per gallon" deal true?
• How many gallons of water am I conserving if I don't flush my toilet for an entire year?
• Why, in America, does soda come in liters but milk and water comes in quarts and gallons?