I need help selecting my last fish. I have a 20 gallon tank with java fern and plastic. I have 6 zebra danios, 5 spotted cory catfish, 2 female platies, and my latest addition, a male dwarf gourami. I had intended for him to have a female partner, but the stores who claimed to have females, actually do NOT! One store is telling me that the females will just come in with the males from time to time--but I'm skeptical. I'm reluctant to pay $30 for a female mail-order, but I will if my male really needs company. Should I hold out for a female for him, or just get a couple more platies?