Right now I have one female leopard gecko in her own tank, she is 4 years old and has never been housed in a group,except when she was temporarily with other hatchlings. I was planning on buying another female leo and waiting until she was about a year old to house her with my other female. They would be in a 20 gallon long tank. I think this should be okay, but I just wanted to get someone elses opinion on it.