Aeranha and Chronotized Aeranha ("Time Sharks") are ferocious flying predators related to the mundane breed of fish known as piranha.  Slightly larger then their non-magical kin, they are transparent,  fly in schools that inhabit cloud banks above the Amazon Basin and never spend time in the water or on land .  Aeranha are attracted to and feed on mana.  They can subsist by maintaining close proximity above a leyline but they are driven into feeding frenzies by magical creatures or persons that travel too close  within their range of scent.  A large enough school has been known to drop the picked-clean bones of a juvenile dragon from the sky.  They present a particular hazard to Magimundi citizens who travel through their aerial hunting grounds not only due to their numbers and speed, but also due to the soporific venom their bite injects.  In sufficient quantities they can put even the largest predator to sleep.   Furthermore, their unique bond with time grants them the ability to "phase" through solid objects and protective garments as well as giving them the ability to "blink" which renders them particularly elusive.   The life cycle of an aeranha begins in the intersticial spaces of the time stream itself where their eggs are laid.  When the eggs hatch, the juvenile aeranha are born into our reality where they grow to maturity.   Aeranha ultimately enter a final stage of maturity where they re-enter the time stream and swim upstream to spawn.  These chonotized aeranha spend the remainder of their lives within the time stream.   During this chronotized phase of their existence, they become even more aggressive, are no longer constrained to certain geographical hunting grounds, and are drawn to disturbances or alterations anywhere in the time stream.  They are the prime hazard of time travel and the sole reason why major time alterations are unheard of.  

"Those who seek to change history have a date with an Aeranha."