I recently started researching animals that can coexist in one cage. So far(from what I have seen) my best option is the three above. The skink can’t be changed out but the other 2 I’m not certain about yet. I’m doing this as part of my capstone(a project needed to graduate high school) so don’t suggest I keep them separate. I know that would be ideal for all of them, but the point of it is to see if I can do it. The tank would be at least 125 gallons, and I know I need to select a sub species of blue tongue skink that lives in a hotter climate or just different animals to go with it. I have 2 years to do this project so this is just some of my initial research, and I don’t plan on doing any of this for at least another year.