I made a simple grammer error because I was typing fast. In my post I accidentally said I would recommend insted I wouldn't recommend, which is what I mean't to say. If you read my post carefully you can tell I am advising not to keep 3 mossies in a 15 gallon. My post is below and I capitallized the part where my grammer error is.
I think you could add another pair to your group but I would not recommend it for a number of reasons. First of all, even though your cage is big with your cage size you are only allowing approx. 10 gallons per. mossy I think about 15 gallons per. mossy is better. And second of all I think it would make things very difficult in keeping tract of feeding, breeding, and the health of the geckos. I WOULDN'T recommend keeping a trio Mossies in a 15 gallon, something larger would definatly be better. Thats only five gallons per gecko. I maintain a pair of U.pietschmanni, which is similiar in size to a mossy in a 2ftx2ftx2ft cage and keep newly WC geckos single in quarantine in 10gallons.
-Matt
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