My first monitor was a Timor that I kept in a 65 gallon aquarium. I was never happy with the monitor because all he did was hide. Occasionally he would climb on the limbs to the basking spot, but would take off to his hide whenever he saw me.
I had another timor that I kept in a 4x2x4 enclosure and the monitor watched me. This one seemed alot more tolorant of me. He was cool as heck.
I think what made the second one more enjoyable was the fact that he felt more secure and content since he had plenty of area to climb and be acive. I am thinking of getting a trio and keeping in the second cage I described.
I would not recomend an aquarium for them. I also would not recomend a reptarium either. Get 2 pieces of plywood and some screws. You can cut them or have the store cut the wood, then screw the pieces together. Buy a sheet of plexiglass and put hinges on it and the front of the cage. Put in a water dish, a bunch of limbs, and some dirt on the botom (protect the bottom from the dirt.) This will be a lot cheaper than an aquarium or reptarium and will give the animals a lot more room. Keep in mind this is a very basic cage
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Ed
There are chameleons, pythons, and monitors in my jungle room.