At what age do they stop growing?

[skinnyrascal]

He could be, more or less, topped out at that size and age as 5-7 ft is average for male Colombian BCIs (which aren't technically "red tails"). What you don't want to do is stuff these guys with food to try to make them bigger: you'll end up with an unhealthy and obese snake with a shorter life span. I only feed my adult boas every 2-3 weeks as well and wouldn't never push a large/extra large/small rabbit on them every week: just not healthy IMO.

If you want a big snake get a species that gets big: just realize what you'll be getting into! Retics, Annies, Burms, Coastal carpets, Scrub python, true BCC boas, and BCOs are some suggestions. Even a female Colombian could get to around 8' but again, it depends on the individual on a healthy non-pushing feed schedule and it usually takes them many years to reach larger sizes.

I thought 8-10 feet was more like it? 5 feet seems very small...my female ball python might reach that size.