Maybe Atomic Turquoise or Water Nixie (from dollyhair.com). If you have Majesty compare her hair and Tootsies hairs and see (Majesty has Water nixie color). Or compare to Bubbles hair, shes hair is Atomic t.
Also there might be a issues were no exact macth can be found because Tootsie hair might have exposed to the sun and her hair is faded from original color etc.
Congrats for finding a new pony
Besides Bubbles ponies like Buttons, Firefly, Tux N Tails, Sprinkles and rainbow ponies blue color should be the same as Atomic Turquoise. If you have on of those you can try to compare them together . But I hope that Water Nixie will be match
I do have Sprinkles and it seems to be very similar in color. If the hair comes in and it's not a match at all I can take some of the tail to rehair the mane and use the Water Nixie to do the tail and no one will be able to tell the difference without putting the tail next to the mane.