Postby Cenetri » Sun Mar 17, 2013 9:07 am
Like Richard said, there really isn't any specific age. You're probably more likely to see it the older they get, but it definitely can take a long time to start occurring, if you even notice it. Sometimes substrates can hide sperm plugs pretty well.
Just as an example, my northern Phineas started dropping at about the 5-6 month mark.
1.0 Northern Phineas