I inherited these fish with a tank I bought today. I started a thread in general aquaria but I thought I would get more response here. I know the red ones are Red Devils but can you tell male or female? What kind of knife is it? What is the little green faced fish? Will these fish do ok in a 55 gal for tonight as the tank I bought was a filthy mess. I have never messed with any of these types of fish and any and all help will be greatly appreciated!!!