so far my alpha Ps are very aggressive and pushy. Usually size doesnt matter. My alpha Cariba is 9.5" and the two fish that are bigger are much bigger. If you have an alpha P, it is usually obvious, they are the jerk of the crew
I dont' know If anyone else thinks of this analogy, but I
look at pygo's as sort of a wolfpack and as the pack
experiences each other and becomes comfortable, then
a 'leader' will arise hence the ALPHA. I believe this will
happen over time and be determined by the amount of p's
and the time they have been together. Another question
arises: will the Alpha be male or female? or does it matter?
As far as the determination being size or aggressiveness,
I agree those two criteria should be met to gain Alpha status.
One more thought crosses my mind as to what the non-alpha fish
do to contribute to the shoal. Is it a constant power struggle?
Do the non-alphas try to gain status or rank? Some good questions
to ponder. The observations by different hobbyists in their home aquarium
limits the validity of the answers to those questions. But those observations
are the catalyst to curiosity and keeps us intrigued by Piranhas.
My alpha piranha also is not the biggest in the tank. I am not quite sure if mine is a female or male yet. But shoaling is fine, they follow him when they shoal since hes the alpha. But they always compete over food and try to stuff there selves. He is the hardest worker when it comes to eating big feeders though. He never stops chasing down that feeder until he gets a grasp on it, and he actually comes back and gives some to the rest of the pack.