Guppy Split Tail

[freddythefish]

A couple of days ago I noticed my guppies tail was split in a couple of places...it didn't look like someone had nipped it (and no-one would cos hes the 'daddy' of the tank) but I don't know what it is.
He is about a year old now so is it old age setting in?

 

[modaz]

the boy is defo old, if you got him from a shop he wouldve been around 5 months+ so your looking at a great age for him,