Thank you for your answers.

Hey, John, that's a great-looking male you have! He is really big and I expect he's at least 10 years old.
Btw I've read that 20-25 years is realistic life expectancy for this species, and specimens of over 50 years old are not unknown.

Here's my bigest male (age uncertain, for he was purchased as an adult 4 years ago):
Image