From my previous thread, I said pygo keeping and serra keeping has nothing much difference and made some serra lovers disappointed
. Here I'm going to make them again disappointed
by letting you know this fact. 
who can terrorize the foreign waters ? pygo or serra........ THE ANSWER IS PYGO
Here are some facts....
Serra is smooth (not tough) fish (when compared to RBP) who can die very quickly because of many reasons. And it is hard to breed them in captivity and grow slowly.
Pygo is a very strong fish who will not die because of small cases and they can adopt to different types of waters and breed quickly. Also they can become bigger within several months unlike the serra.
Also pygo is involving in pack hunting which can do much more harm than a single or few serras can do in wild.
So pygo can terrorize foreign waters, and serra can terrorize it's own tank sometimes.
So pygo is more dangerous than serra.
by letting you know this fact. 
who can terrorize the foreign waters ? pygo or serra........ THE ANSWER IS PYGO
Here are some facts....
Serra is smooth (not tough) fish (when compared to RBP) who can die very quickly because of many reasons. And it is hard to breed them in captivity and grow slowly.
Pygo is a very strong fish who will not die because of small cases and they can adopt to different types of waters and breed quickly. Also they can become bigger within several months unlike the serra.
Also pygo is involving in pack hunting which can do much more harm than a single or few serras can do in wild.
So pygo can terrorize foreign waters, and serra can terrorize it's own tank sometimes.
So pygo is more dangerous than serra.