jcm412;2729927; said:
about what size do they begin to slow down in growth
are you asking out of curiosity, or because you are considering keeping the fish? if it is the former then it depends on a lot of circumstances...housing, feeding, genetics, other environmental factors. either way, they get big fast...easily 2' in their first year in many cases, sometimes larger sometimes smaller. they are the most aggressive of the family. it's not uncommon to see 3' long gator gars housed in private aquaria, and 6-7' is quite frequent in zoos.
if you are asking because of the latter, then my info is the same with the addition that you shouldn't be considering keeping the fish if you are still asking the questions presented in your first post. i would highly suggest researching further (finding out about the largest gar species can be much more quickly done -and probably with better info- by going to books or non-forum sources), and going with keeping the much more reasonable (for home aquaria) Florida gar - most commonly available in pet stores.--
--solomon