fish stock compatbilty

i have a 60 gallon tank with 3 columbian tetras and 2 dwarf gourami my ph is 7-8 My water Ph is 6.5-8.5 the hardness is 3 for my tap water I use api tap water conditioner and a marine land filter and a 60 gallon heater

Hey everyone!         I have a 40 gallon tank set up, I was looking for some fish ideas to stock it with. It is a semi-aggressive tank and I have an idea on how I'd like to stock it but I want to hear it from the experts  . I currently have:   x6 Tiger Barbs (1 is a green) originally 8 with 3...