In the wild, geckos are solitary animals, spending time together only when it's necessary for mating. The females don't even spend any time caring for their youngsters. Despite their loner nature, however, some geckos can live peacefully together, as long as you follow some basic guidelines regarding the mixing of different sexes, species and sizes.
Pairs and Groups
A male and female gecko pair can live happily together in a single tank or enclosure. Likewise, a group of females and a single male can also live together with the proper amount of space and care. A typical gecko group consists of four to five females and a single male. Multiple females can be kept together with a male, but multiple males should not be kept together, even with several females, since they will fight over territory.
If a male and female gecko are housed together, they will breed. A male kept with a group of females will mate with most of, if not all, the females. The females will lay eggs, which can either be removed from the enclosure and placed in a safe place for hatching, or left where they were laid. The females will not care for, sit on or protect the eggs. Once the young geckos hatch, they should be placed in their own tank since adults may harm the small hatchlings.
When geckos are housed together, either in pairs or groups, they should all be about the same size or body weight. Smaller geckos are often picked on by larger ones, and may get injured or pushed away from food. A tiny gecko that feels intimidated by others may spend most of his time in hiding, so it is hard to see that he is being bullied.
Different species of geckos should not be housed together, even in mixed-sex pairs. Use a separate tank or enclosure for each species of gecko that you plan to keep. For example, keep only leopard geckos with other leopard geckos, and crested geckos only with other crested geckos.
Even if your geckos would otherwise get along well, either as a pair or in a group, problems may crop up if you don't provide enough space for each individual. They may begin to fight over space, food or water. The stress of overcrowding can lead to illness. The amount of space needed depends on the species. Crested geckos, for example, need plenty of room at about 20 gallons of tank space for each individual. House and leopard geckos can live together in smaller enclosures, with a 20-gallon tank suitable for a pair of leopard geckos and a 30-gallon tank suitable for a group of four to five house geckos. Although a bigger space is better, don't make the enclosure so large that the geckos have trouble hunting down live food or you have difficulty keeping it clean.