i am of the same opinion as insinuasian on this one when a pygo is sml it has to contend with a lot of predators (other pygos) that it shaols with so as a good defence mech it grows at a really fast rate to give it a better chance of survival.InSinUAsian said:IMO i think that pygos grow faster then serras due to the fact that there is competiton to out grow others in the same school. Since serras are usuallysolitary there is no competition with other fish in the same tank to grow fast. I think that if a pygo was solitary in its own tank it would grow just as slow as a serra.
Ohh and just as a comparison, and maybe this applies only to spilo and not other serras, but my spilo school behaves much like my old pygo school. Not much differnce except a little more aggression. Feeding, growth and activity are all pretty much the same as when I had equal sized schools of reds. I think that its the school enviroment that pushes the fish to grow faster. Each fish trying to out compete the others to be the biggest and usually most dominant.
That is why i think that serra's usually grow slower then their schooling pygo counterparts. Just my two cents.
Serras are mainly fin nippers, feeding on the fins of fish. There diet does include plant matter but I dont think it is their main food.o snap its eric said:Pygo is pretty much all meat while serra is mostly fruit and nuts and sometimes small fish.
i know gir sometimes i amaze myself hahahahahaGIR said:TerrOr-
The best HYPOTHESIS that I have heard is the one that InSinUAsian stated and DiXoN adds very good points. He is right that noone know for sure, and it will remain that way until someone takes it upon themselves do discover the answer to your question.