A 72 gallon bow tank with 1 red tiger Oscar 2 pitcus catfishs and 2 blood parrots Could you add more fish to your tank?

The tank certainly could hold more fish but I would be at a loss to suggest a species you could/should add. The basic rule is "1 inch of fish needs a minium of 1 gallon of water". So applying the rule and adding 50% to be on the safe side. An Oscar needs about 15 gallons (15) a Pictus catfish about 6 gallons (12) and a Blood Parrot about 14 gallons. (28) so adding them all together equals 55 gallons.