Do Feeder Fish And Neons Breed Easy Or Aquatic Frogs?

How CAn U Tell The Difference Between A Male And A Female Aquatic Frog? Or Feeder or neon. I Have a Male ANd a Female Guppie But Just Wondering ABout THe Other Fishys In My Tank. ANd How Can U Tell If Ur Fish Are Sick., Need SOme Advice on THese Things