Out of the species I have cared for (aurantiaca, viridis, laevigata, expectata, madagascariensis and crocea) male aurantiaca, expectata and crocea are very bold, females seem to be a little on the shy-side. M. viridis and madagascariensis are cautious about coming out in the open while your around and often choose to remain hidden unless there is food around.
I have had few problems keeping male mantella frogs together even though they are very territorial. Male aurantiaca will wrestle over territory. I have heard of situations where small, weak, or unhealthy males were bullied out of food by stronger ones so it's important to keep an eye on any small frogs. I would also recomend keeping wild-caught mantellas in seperate enclosures for at least a few weeks prior to housing them together so that weak or unhealthy frogs have time to put on some weight and be medicated if needed. Good luck,
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Devin Edmonds
devin@amphibiancare.com
www.amphibiancare.com