Im getting a mystery snail?

Question

and i dont want to end up with a million of snails help?

Answer 1

Firstly mystery snails are not hermaphrodites, which means you will need both a male and female to breed.  (you say you are only getting one?)  Secondly they need special conditions to breed, you need to have 3-5" between the waterline and the top of the tank as they lay their eggs above the water.  As the other answerer said you can remove the eggs if you don't want babies.  

Answer 2

mystery snails are best kept in pounds that way when they over populate the pond fish will consume the  majority of the snails

Answer 3

Mystery snails are not like other prolific breeders such as the common pond snail (cone spiral shell) ramshorn (circular shell) or the malaysian snail (hard cone spiral shell)  While the above I have listed lay their eggs in the water (exept malaysian snails which have live young) , mystery snails and apple snails lay their eggs out of the water a few centimetres above from the water's surface. When you see the eggs (orange stuff) you simply scrap it away using a knife or break it off with your hands. If the eggs managed to hatch before you scrap them away, and fall into the water, putting in a lettuce over night will attract the snails. In the morning, you can simply take out the lettuce leaf with most of the snails. Repeat until problem eradicated.

Warning: If you some how have a break out of snails, avoid using clown loaches and crayfishes. Instead of reducing the numbers they will eat ALL of your snails.

Heres a site with lots of pictures and shows what I mean when they lay their eggs out of the water.

http://aqualandpetsplus.com/Bug,%20Snail...