Hi im from aus and had a few over the years im growing one out now hes about 3.5 inch and eats gold fish more than half hes size can not put with other fish as they are very aggresive as for cold water they can tolerate cold water down to about 12-15c no lower as in winter here it gets down to 10c or lower so good luck if you plan to keep inside temp 24c and a tank at least 8x3x3.