Not possible. Larval forms 10-15mm SL the gonads and/or ovaries would be visible under microscope. The rest as to age is roll of the dice to determine sexual dimorphism. I might also add this portion to the seemingly constant application that males tend to color up more than females.at that size you may be able to see their organs with a bright light
What this means is that camoflage plays an important part to piranas coloring up not just simply attributed to sexual maturation.those were attributed to camouflage parameters. In adults, uniform and specific patterns of the pigmentation were attributed to secondary sexual aspects, which are not associated only to the reproductive period, through intensification in the anal and caudal fins and flanks of the body in males.
Tough one to quantify since both sexes can behave as male or female including coloration. In your aquario, you may be able to observe patterns of behavior that will lead you to conclude that you might have a pair, but the only way it will be known for certain is if spawning occurs. I have seen such behavior of what appeared to be male and female only to discover later the fishes were male after dissection. That is why I say such things are a roll of the dice and why as a general rule you cannot simply look into a dealers tank or friends and say for certain that is male or that is female. Not even the most dedicated field researcher can do that with any certainty and again, those that claim to be able to do it should publish their observations so that science can review it and ask questions. This will require proof with dissected specimens of before and after, authenticated and supervised by a PhD. Simply taking a person at their word or doctored photos will not suffice.Is there away to asses a probability to a paticular fish (particulary Serras) as being a male by observing behavior?
Not really, since piranas are variable on size and age when they are sexually mature. There is nothing in concrete about what size they are ready for this. All studies so far indicate maturation is around 2 years but that could be 2 or more years depending on many factors (ie., water conditions and climate). Size does not seem to factor in much." its not the sex that determines size, but the size that determines sex"
Again, there are many mitigating factors, one is as you described. Granted some studies, published by people who breed piranas indicate that females have larger girth vs. male which is slimmer, but this is on captive bred piranas where the hobbyists monitors his fishes on almost daily basis. If you put them (the hobbyist) into a situation where he must sort out piranas from a store or in nature, his success of picking out males from females drops to zero.But was curious if males and females have this same characteristic(the bulge in their stomach) or could this just be that they got more of the meal then the others?
what I meant is that they stay closer together as a group for support while males prefer to be by themselves
I'm glad you cleared that up because fish are not the same as mammals, not structurally nor in habits, though instinctive behavior may confuse some for being similar. As for males prefering to be by themselves, I'm not sure how you are formulating this opinion. Based on what? Aquario observations? This is a bit far reaching because you are assuming that your few specimens give you the basis for that opinion, am I correct in this evaluation? If so, then you should reevaluate your opinion because it realistically does not hold water (no pun intended).its my opinion, and I said with most animals meaning not all
You are again, making a broad generalization without providing any data to support your opinion. In otherwords, you are saying you have observed of nearly all fish this comparison holds true, yet how many specimens are we talking about? one? two? three? or five thousand?actually I have found that in cases that I have observed of nearly all fish this comparission holds true
Your entitled to your opinion as I am entitled to examine and dissect it for accuracy and substance in piranha science. Your experiences while interesting to some, is still very limited to simple home study analysis with a few fish. You might consider digging a bit deeper in evaluating opinions before stating them so that when you present an argument it is based on strength of evidence than just weak opinion's without credibility. You will note, I allow certain remarks to stand by other members when it is factually written and supported by evidence. In your case, I tend more to reply to you because your opinions are a bit misguided and warrant a bit more of my attention because I do see that you desire to learn. How much you can learn is entirely up to you and what you are getting out of piranha science.however as I said it is my opinion and experiences can vary
If you wish to compare years of experience, I have well over 45 years of experience dealing with piranas in the aquario and scientific examination and I have not seen a single example of what you profess to be fact substantiated by literature and science.but I have kept fish for well over 12 years now
Very simple, you are holding your fish in an unnatural state of environment. Any scientist worth their weight in salt will tell you that is not a serious evaluation of how your fish would behave in the wild. That is supported by a long list of references at my web site. Suggest you look it over and see how references are used to support arguments. I have yet to see any from your arguments.You always tell me that my observations in my own tank hold no meaning to the fish in the wild. So what you are saying is that since a fish is in a much smaller zone it will act completely different. I would like to know how you can support this hyppthesis?
And you have answered your own question, they will not act nor behave the same in an enclosed environment. You can only simulate what you think is an natural environment in hopes the fish will adjust. Some do, some don't. Disagree? then go back and read the unsuccessful stories of keeping captive piranas and those that had little luck in keeping them alive. As for this last remark:Why would a fish say hey, Im in a smaller tank so I will act different, I will agree that they certainly will not do everything the same due to limitations such as traveling and hunting and such.
You are making to much of a personal issue of this where in reality I'm pointing out to you that your experience in such matters is lacking any real perspective. And you are guided by personal opinions on matters that I question to relevancy and accuracy of execution, because you have yet to provide me one single published example of your information supported by science. It is exactly what you make it out to be, personal opinion with a hint of prejudice without merit.Again I am not trying to be a jerk, I just would like to see your view point