I'm relatively new to having aquariums and I want to make sure I'm not going to overstock a 20 gallon high I just set up. I already did a fish less cycle with ammonia for a month and added 8 harlequin rasboras and 4 oto cats. All the parameters have looked good for the past few days, with slightly acidic water(a steady 6.8), 0 ppm ammonia, 0 ppm nitrites, and 10 ppm nitrates(left over from cycling despite numerous water changes, I'll be doing a water change tomorrow to get it down). I also have it planted with wisteria, ludwigia, anubias, rosette swords, some floating plants, and java moss on driftwood. I have a marineland penguin 150 filter rated for 30 gallons and a heater ( I keep it at 78 ). I have sand and smooth pebbles for substrate. I was wondering if in a few weeks I could add some small cories and honey gouramis. I was thinking about 3 or 4 panda cories and 1 male honey gourami. Also, would the cories freak out my otos or overload a part of my tank? I would really like to have the tank slightly under stocked. So would this plan work or should I just go with one type of fish? Thanks in advance!!!