I would put the smaller shortnose in the pond so the koi can have a chance of getting away. If the koi are females then it would be harder for the gars to try to eat cause they are more plump. As for acclimation, I usually just put them in the pond and away they go. I would be more worried if they are going from warmer water to colder pond water. All I can say is expect a growth spurt, you might be needing that 220 before you know it. The shortnose might puff up for a bit but it will go away over night.

