Currently I have 2 red wagtail platies, 3 spotted cories, and 6 zebra danios in my 20 gallon tank (as well as a javafern and plastic plants). I know I don't have room for much more. Is a betta compatible with this group? Can a dwarf guarami be happy alone? Would a school of 5 tetras be too much for this tank? Would the platies be happier in a larger group (not that they seem unhappy.)? So far, this group gets along very well. The danios and corys swim together. Sometimes the platies even hang with them. They're great fun to watch!