In a tiny 5 gallon tank, the 5 guppy males will make s nice stocking. They will not overload the tank and you will not need to deal with fry the way you would with a mix of males and females. Another nice display would be 6 to 8 male endlers. I keep only wild type endlers in a mixed sex colony but some nice males would go a long way to driving interest by a youngster.