Can I put platys in my tank?

I have a 75 gallon tank with 3 common goldfish and 4 mollies. I have a filter that does 330 gallons per hour and an air pump for up to 50 gallons. I d

I have a 75 gallon tank with 3 common goldfish and 4 mollies. I have a filter that does 330 gallons per hour and an air pump for up to 50 gallons. I do bi weekly water changes and keep the tank between 72 and 74

or:I have a 75 gallon tank with 3 common goldfish and 4 mollies. I have a filter that does 330 gallons per hour and an air pump for up to 50 gallons. I do bi weekly water changes and keep the tank between 72 and 74

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