6 will be a good number, you will see much, much better behavior from them as they play together.
I would watch the sword even in a 65g tank, I had one in a 90 gallon aquarium, and it took over more than half of it. also be wary of the roots too they will keep growing even if you trim the leaves.
Also watch the banana plants, it's a lily, so if you don't want a lot of light shaded from the aquarium, then pinch off the pad runners when they appear. before your tank is plunged into darkness.
And once all this quarantine stuff is over, try to find an aquarium, or aquarium plant club around, they can be a great resource for help, folks to talk to about your hobby, and often cheap plants and fish. There's a short list available on the AGA website https://www.aquatic-gardeners.org/links.html, I'm a member of a couple of the clubs on there, and also of the AGA itself.
Otherwise, ask questions, read, take pictures, share it all
)
