Typically a panther male will get a significant change in color by the age of 6 months, but may or may not show color before this. All panthers are born a tan-brown color, and develop their colors as they age. Each individual will also grow at his own pace, with some getting very large very young, and others growing more steadily throughout their first year.
As examples, I present below the photo progression of two very different panther males from the age of 3 months to 12 months. Daedalus (on the left) is a Nosy Faly x Ambanja cross and Cerberus (on the right) is a blue-bar Ambilobe.
|Daedalus (left) and Cerberus (right) at 3 MONTHS OLD. Daedalus was twice as big and already had blues and oranges here and there. Cerberus looked very much like a baby still, only tans and browns.|
|By 4 MONTHS OLD Daedalus was already bigger and his blue-teal color had completely taken over. Cerberus was still very small and still very tan in color. At this point he could have been confused as a female.|
|At 5 MONTHS OLD, Daedalus had grown more still and Cerberus hadn't grown much at all. He was still mostly tan with a few hints of green here and there.|
|Finally, by the age of 6 MONTHS OLD Cerberus was finally catching up color-wise. His greens had become way more prominent, as well as reds and yellows. He was still small for his age. Daedalus on the other hand was still growing nicely.|
|Daedalus got his reds and yellows back just a month later at 10 MONTHS OLD and Cerberus was starting to fire up nearly solid yellow and red. He was also now as big as any typical panther male.|
|At 11 MONTHS OLD both boys look big, healthy, and very colorful. Cerberus was even bigger now than Daedalus, and weighed a good bit more than his blue counterpart.|
So, do not be alarmed, or discouraged, or worried, or anything of the sort if your panther male isn't developing at the pace you think he should be. As long as your husbandry is in order and they are healthy (checking with an experienced vet, a professional, or a reptile forum is a good thing to do if you have doubts or worries about this) there should be no reason to worry. They may catch up in their own time.