similari alle botia:
http://www.springerlink.com/content/159fgu4ht7xh0j9c/
questo da ragione a tutt'e due..
http://www.cs.cmu.edu/~ACO/dimacs/tovey.html
e questo anche , tu per i caracidi e io per i barbi /ciprinidi...
There is more than one type of interaction within a school. Many of the Characins (Tetras) that school have no rank structure or hierarchy within the school. Other fish, most familiarly the Barbs, do have structured schools. Males in particular have a rank order. There is one fish, the alpha male, who "bows" (gives way) to no one. The other males in the aggregation will each have their own distinct rank as well. The beta male (note: beta, second letter of the Greek alphabet, not Betta, the Siamese Fighting Fish) will bow to the alpha, but no other. Similar ranks will exist for the gamma, delta, and so on to the effective omega, low man on the totem pole (a mistaken analogy, as that is really the prime pole position, or so I've been told). These fish have a hierarchy and each "knows" its position in the school organization chart. This is exactly like pecking order in chickens.