Juvenile Dorado Aggression Question

[Chicxulub]

Outstanding post, Matt!

It is awesome to see that a hypothesis is actually sound and on its way to becoming theory. It makes sense that there's more to the difference of these two species than JUST allopatric speciation (speciation via geographic dispersal). I figured that adaptations to water qualities likely were an effect. While this doesn't prove me right, it does support the idea.




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[dogofwar]

Along with the really wide distribution of S. brasiliensis is the diversity of fish with which it co-habitates.

For example, in a big river (like Rio Uruguay), Dorado are swimming around with big catfish, other big characins, giant rays, etc.

In Laguna del Diario (see picture below...that hotel is across the street from the beach / Atlantic Ocean), Dorado (like this guy...one of many we caught) are living with lots of small fish (livebearers, cichlids, etc.) and even saltwater fish (like the guy in the middle picture...whatever it is) that find their way into the pond.

Matt

 

[DB junkie]

Matt, few questions for you.....

Being someone with so much contact with these fish is it easy for you to tell the difference between Frankies and Brassies?

IF Brasiliensis are so plentiful and found everywhere then why are they under a quota? Or is the whole quota thing just a line to get more money for a fish????

 

[dogofwar]

No idea on the quotas. I've always caught and released them, including big ones on the Rio Uruguay. They're available at restaurants too, but only in season.

S. franciscanus are only found in the São Francisco basin of Brazil. S. brasiliensis are found all over the place, including all over Uruguay.

I'm relying on Felipe Cantera for identification. And he probably knows more than any living (or dead) person about the freshwater fish of Uruguay

Bringing in fish from Uruguay is not an easy or inexpensive thing, whether the fish is abundant or less common.

Matt

Matt, few questions for you.....

Being someone with so much contact with these fish is it easy for you to tell the difference between Frankies and Brassies?

IF Brasiliensis are so plentiful and found everywhere then why are they under a quota? Or is the whole quota thing just a line to get more money for a fish????

 

[DB junkie]

So that pointy nosed lil guy in the pic is a Brasiliensis? I always thought they had a much more rounded head - at least the one I raised did.

I'm more confused then ever about Dorado after this thread.....

 

[dogofwar]

Middle pic above is some kind of saltwater fish...caught in the same seine pull as S. brasiliensis (in Laguna del Diario, Maldonado, Uruguay). Crazy to think that they're found together!

Matt

So that pointy nosed lil guy in the pic is a Brasiliensis? I always thought they had a much more rounded head - at least the one I raised did.

I'm more confused then ever about Dorado after this thread.....

 

[dogofwar]

As an aside, here's what the temperature looks like over the course of the year, where they're found. Far from tropical...



Matt

 

[Chicxulub]

So that pointy nosed lil guy in the pic is a Brasiliensis? I always thought they had a much more rounded head - at least the one I raised did.

I'm more confused then ever about Dorado after this thread.....

Looks like brassy head to me. It's just tiny. :shrug:

 

[dogofwar]

Here's another S. brasiliensis and a couple more from another pull of the seine.

The type locality for Australoheros facetus (the chanchito) as described by Darwin's crew (the fish I was after)

Can't tell whether these two little ones were also S. brasiliensis or red-tailed barracuda (crappy picture)...

Matt

 

[crenicichla444]

Here's another S. brasiliensis and a couple more from another pull of the seine.

The type locality for Australoheros facetus (the chanchito) as described by Darwin's crew (the fish I was after)

Can't tell whether these two little ones were also S. brasiliensis or red-tailed barracuda (crappy picture)...

Matt

View attachment 1033433View attachment 1033434View attachment 1033435View attachment 1033436

For some reason none of the fish above look like dorados, only look like some sort of predatory characin with a red tail...


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