whats going on is it maybe a female??

[rxracer]

ok i have 4 RBP in my 30g tank. in august im getting my 75g, but they are like 1 to 1.5 inches right now. i have two that are growing god and their rear lower fin is all red. than i have one midle size one, than one that is 1/2 the size of the bigger ones. i dont know whats going on i also niticed that it doesnt have the red in the fin like the rest. is there a way to tell if it is a female or any ideas why this one would not be growing well. ive had them since june 28 and the big ones have doubled in size almost. any ideas are helpfull!!
thanks
Rob

 

[DiXoN]

its just a slow grower and probably the runt of the group.
as for the red it may come or it may not.
you cant tell males or females almost all piranha are not sexually dimorphic

 

[rxracer]

well i learn something new every day.. thanx a bunch

 

[Ruger345]

It's almost impossible to tell them apart until you see them in their breeding colors/clearing a nest.

 

[RuXPiN]

very normal to have different sizes, thats why you buy 6 or 7 if you want 3 or 4, your smaller ones will probly get eaten by the bigger ones, very soon actually, the big ones will eat 80% of there body wieght every day, thats why they grow so fast, the little ones will have to fight for scraps. this has been my experience in almost 20 years of having p