The smallest gars get to be 24" to 30" in length you could get a Hujeta gar that is in fact a Hujeta Pike Characin when you say Orange I am 99% sure there is no Orange Gar but have you confused it with a Orange pike like this one but it will not stay Orange going a lot darker and gets quite large and quite aggressive..
there is also the half beak gar that has to be the smalles it's probably not as true gar but full grown adult size is.....1 1/2 - 2 inchs watch out for this monster everyone i have 3 of these