What can you tell me about this snAke?

[PghBall]

i also noticed he has some awesome green eyes :-D they look pretty neat.. and why should he be alone? are they more prone to being agressive?

Quarantine keeps your collection safe from mite infestations, transmitable disease, etc. Nothing to do with aggressiveness. Better safe than sorry. Most here recommend a minimum of 6 weeks quarantine in a different room of the house (different floor as well) to minimize harm to your collection. After the quarantine period passes, the snake can then join the collection.