First, WAIT UNTIL THE COPEPOD COUNT IS REALLY HIGH!!! They require a lot of food readily available at all times. If they do not have food, they will starve. The way to tel a female and a male apart is the front dorsal(top) fin. They have two dorsal fins and the front one tells you what you need to know. The male's front dorsal fin comes out to a long point, where the female's is just like a regular doral fin flattened at the top...you can see the difference if you look closely. Also, I recommend only getting them as a pair, because a male will not always accept a female and will many times attack her until death. Males are very vicious towards themselves, but not many other fish. They are usually very docile fish who spend their days eating, but two males, and even sometimes a male and a female, will fight until the death. Find them as a pair, or monitor very, very closely for the first few days and until they have become accustomed to each other. I just lucked out by finding two that fell in love before I picked them up. Great fish, but very difficult to keep healthy and even harder to pair. Once paired, though, they can and usually will mate in an aquarium.