I have 65 gallon (the dimensions are 38x18x21) with 2 separate filters filtering about 300 gallons per hour each. I have a 6in hujeta gar, a 6 in dinosaur bichir, a 4 in African brown knife, and 4 4in gouramis ( 2 gold and 2 blue). Is this overstocked? If not, could I add something such as 2...