With all of the recent interest in Dorados and the question of what causes the observed wide differences in what appears to be a Golden Dorado, I am opening this thread as the official place of discussion for this genus. The ultimate goal is to come to a group consensus of what makes a Dorado a particular species in order to create an ID thread to sticky.
I've figured out why there are big headed Argentinian Dorados and small headed Brazilian ones. The rest should be fairly easy.
There has been marked interest in the community in discovering exactly what is what in the genus Salminus. This is the place where we will discuss this problem and hopefully discover answers. Please share any discoveries you make here. Published articles in .pdf format or otherwise are preferred.
Several questions of interest to address:
1- What is the difference between the Argentinian and Brazilian Golden Dorados?
2- Is Salminus maxillosus actually separate from S. brasiliensis?
3- Is it possible that the Brazilian Dorados are a separate species than the Argentinian ones?
4- Why is there such a wide variety in the color of Golden Dorados? What causes it?
After doing some research of my own, I'm fairly certain I have an answer for at least one of those.
The answer to question number three is simple: the Brazilian Salminus are, confusingly, NOT Salminus brasiliensis. The Golden Dorados that are from Brazil and which are raised in farms have been known to science since at least 1850 in the form of Salminus cuvieri which was later described as a junior synonym of Salminus brasiliensis. The validity of the two-species approach to the answer of the Golden Dorado was hotly contested in the literature until Lima and Britski addressed the issue with a survey of the populations of Golden Dorados in 2007.
The answer they came up with was that there are in fact two separate species of Golden Dorado, the big headed Argentinian species which is known in modern literature as Salminus brasiliensis and a very similar, smaller headed Brazilian variety that was not yet properly described. Based on the results of their investigation, they found that it was correct to consider the Brazilian population separate based on unique morphological traits in their scales and dentition. Based on this evidence, Lima and Britski separated the Brazilian Golden Dorado population from the Argentinian S. brasiliensis into a new species which they called Salminus franciscanus, which has been reviewed and accepted as correct.
Image credit to Lima & Britski, 2007.
So in short, there are in fact two different kinds of Golden Dorado, brasiliensis from Argentina and franciscanus from Brazil; you're correct to say you have a Golden Dorado if you own either.
Can anyone dig up anyhing interesting on affinis or hilarii?
Reference:
Lima, F. & Britski, H. (2007). Salminus franciscanus, a new species from the rio São Francisco basin, Brazil (Ostariophysi: Characiformes: Characidae). Neotropical Ichthyology 5 (3).
I've figured out why there are big headed Argentinian Dorados and small headed Brazilian ones. The rest should be fairly easy.
There has been marked interest in the community in discovering exactly what is what in the genus Salminus. This is the place where we will discuss this problem and hopefully discover answers. Please share any discoveries you make here. Published articles in .pdf format or otherwise are preferred.
Several questions of interest to address:
1- What is the difference between the Argentinian and Brazilian Golden Dorados?
2- Is Salminus maxillosus actually separate from S. brasiliensis?
3- Is it possible that the Brazilian Dorados are a separate species than the Argentinian ones?
4- Why is there such a wide variety in the color of Golden Dorados? What causes it?
After doing some research of my own, I'm fairly certain I have an answer for at least one of those.
The answer to question number three is simple: the Brazilian Salminus are, confusingly, NOT Salminus brasiliensis. The Golden Dorados that are from Brazil and which are raised in farms have been known to science since at least 1850 in the form of Salminus cuvieri which was later described as a junior synonym of Salminus brasiliensis. The validity of the two-species approach to the answer of the Golden Dorado was hotly contested in the literature until Lima and Britski addressed the issue with a survey of the populations of Golden Dorados in 2007.
The answer they came up with was that there are in fact two separate species of Golden Dorado, the big headed Argentinian species which is known in modern literature as Salminus brasiliensis and a very similar, smaller headed Brazilian variety that was not yet properly described. Based on the results of their investigation, they found that it was correct to consider the Brazilian population separate based on unique morphological traits in their scales and dentition. Based on this evidence, Lima and Britski separated the Brazilian Golden Dorado population from the Argentinian S. brasiliensis into a new species which they called Salminus franciscanus, which has been reviewed and accepted as correct.
Image credit to Lima & Britski, 2007.
So in short, there are in fact two different kinds of Golden Dorado, brasiliensis from Argentina and franciscanus from Brazil; you're correct to say you have a Golden Dorado if you own either.
Can anyone dig up anyhing interesting on affinis or hilarii?
Reference:
Lima, F. & Britski, H. (2007). Salminus franciscanus, a new species from the rio São Francisco basin, Brazil (Ostariophysi: Characiformes: Characidae). Neotropical Ichthyology 5 (3).
No eating in spurts here. I wouldn't be surprised if at this rate the Argy catches the other Dorado here by the end of the year (knock on wood) but it could just be beginners luck too.... 
