I use 20 gallon longs for 3 geckos and they all seem to love one another but they also always have 4 places to hide to get away from one another. I will only temp a male in with girls because they seem to stress a girl out but 3 girls together np.
The plan was one male and two females but I see that that wont work in a 20 gallon. My custom cage will have a little more surface area than a 55 gallon so I could probably house the trio in there, right?