The gender of a gar can be determined via testing, hormone injections, or by actually seeing the gar laying eggs/producing milt.
So, if you wanna start breeding Gars. you gotta buy atleast 5 gars or something and hope for diffrent sex?
Usually with breeding it is recomended to buy 6 individuals. This gives you something like a 99% chance of having both males and females. With gars though since the spawning triggers are not knowneven doing this is unlikely to result in the gars breeding. Unless you have access to the hormones fish farms use you will probably be out of luck.
Actually we have a pretty good idea of what the spawning triggers are and how to go about it. It all has to deal with Condition, age, photoperiod, temp and ratio of sexes used in the spawning group. Spawning these fish in captive conditions on the hobby level is not done mostly due to lack of any of the above required conditions. It is intensely difficult also in many cases to properly sequence the required conditions in captivity. It has been done and can be done if one is very patient and very attentive to details, Helps to have deep pockets too......