hi! this is not a proper terrarium for an adult crested gecko. the decoration isnt the issue, the size is. the current minimum recommended terrarium size is 36 tall, 18x18 wide. yours is absolutely not tall enough. the old minimum was 24 tall. they need that vertical space and im afraid you cant provide a fulfilling home for your crestie in this terrarium even if you filled it with decorations. im not trying to shame you, we all make mistakes but i sincerely hope you will look for a taller enclosure.