I have had a 10 gallon fish tank which i fully cycled. It contains a small piece of wood, sword plant, bannana plant, lilies, and a 20 gallon sponge filter. For fish I have a male betta, 2 emerald Corey cat fish, and 2 albino cory cat fish. I know the general rule of thumb is 1" per gallon, but because of the filter and plants would it be okay if I added another one or two Corey cat fish?