Salminus Questions for the Community

[Andrew_Murphy]

Hi all,

I'll start with a teaser.

https://i.imgur.com/5rB0mOE.gifv

Apologies for the lack of updates. At a recent conference I was able to speak at length with a few colleagues regarding the lineage of these animals. Given the genetic diversity of the species, dentition, and the overwhelming likelihood that these animals are a product of aquaculture, I am comfortable calling these brasiliensis with a degree of confidence. We're currently working out the logistics of running genetics and hopefully collaborating with São Paulo University to build a clear(er) picture of subpopulations within the species and how/where they are being utilized commercially.

Population is stable at ~47 animals. Largest animals are still around 75cm but the median group has grown considerably. Largest males spar intermittently, with a lot of tail bites. I currently have at least 3 gravid females but I doubt they will spawn naturally, despite a lot of interesting interactions and courtship behaviors from the larger class of males(still trying to get this on video). Once we get more holding freed up, I may see if other institutions are interested in IVF offspring but there are a lot of hurtles to overcome prior to that move.

Next steps here are introducing other species into the exhibit. If all goes according to plan in grow out, I should have 60 Myleus introduced into the system by late July. Currently growing out a massive school of Triportheus for possible inclusion along with some, Sevs, Acarichthys and G. altifrons, though these will all take a while to get to appropriate size). Next accessions for this exhibit will be a large school of Prochilodus, Cichla, and Caquitaia. Trying to get a hold of some platinum cats(B. rousseauxii) before a 5000g grow out opens up.

Will update once I can get some better shots.

Cheers,
Andrew

 

[moe214]

Look forward to your updates! . And boy am I getting confused with dorado ID now. What I'm hearing is going against their taxonomic descriptions. Of the specimens we've seen anyway.

 

[headbanger_jib]

What a read!!!

Really awesome setup too.

 

[Chicxulub]

When I occasionally log in, I'm following this thread with a keen interest.

It's becoming readily apparent that the head shape thing will have to go away now. That was always anecdotal and was never intended to be anything but anecdotal; a rough guideline for reference, not a gospel truth. Seeing your brasiliensis (and with your credentials, I trust your diagnosis completely), it is apparent that the Brazilian fish are morphologically different (or at least have provided us with a broader sampling of what exists) than the Argentinian fish that led us to that conclusion, while still being the same species.

Given that brasiliensis is also (maybe exclusively) farmed, the assumption that farmed fish are all franciscanus could very well be wrong. Could I get your thoughts on this please?

Also, if you could be so kind, have you noticed anything egregiously wrong with the guide, or anything that you'd like to add (credited, of course)? I hope to further clarify and sharpen our communal knowledge of this genus with your help.

 

[moe214]

When I occasionally log in, I'm following this thread with a keen interest.

It's becoming readily apparent that the head shape thing will have to go away now. That was always anecdotal and was never intended to be anything but anecdotal; a rough guideline for reference, not a gospel truth. Seeing your brasiliensis (and with your credentials, I trust your diagnosis completely), it is apparent that the Brazilian fish are morphologically different (or at least have provided us with a broader sampling of what exists) than the Argentinian fish that led us to that conclusion, while still being the same species.

Given that brasiliensis is also (maybe exclusively) farmed, the assumption that farmed fish are all franciscanus could very well be wrong. Could I get your thoughts on this please?

Also, if you could be so kind, have you noticed anything egregiously wrong with the guide, or anything that you'd like to add (credited, of course)? I hope to further clarify and sharpen our communal knowledge of this genus with your help.

I think what is making it hard is the fact that the taxonomic description isn't specific about where to count the scales between the LL and dorsal. That's what it is for me anyway. Because we've been counting at the rear end of the dorsal I feel that was always key to ID, and being only one instance where the head thing proved invalid to ID, one would put some trust in it. But as we know it was never for sure.

That being said, I remember Wes saying frankies were the ones aquacultured which was why we got so many frankies and never brasiliensis; which makes sense. However now we are hearing the opposite from the OP and rapps. Confused I stay lol.

 

[Chicxulub]

I'm confused too lol. I've got the same data as we've always had, but a severe lack of access to fish on which to test it. Thr LL counts on these have given me fits over the years. The place to count them is normally supposed to be at the dorsal fin insertion. The reason I went to the rear of the fin is because I was getting scale counts of 20+ on some fish at the origin, which should be too many for anything in this genus.

Mr. Murphy here brings both enough fish to the table and the expertise as to likely help us sort this out. I'm a fisheries biologist, but I do mainly field work and I only have three years experience as a professional. Mr. Murphy is literally living that which is my goal in life. I'm inclined to defer to him LOL! Whatever guidance he gives me with his hands on work with these fish is what I'll put into the Guide. I spent several thousand dollars on ATF to sort that out, but when I broke my back and my military career ended abruptly, I had to go back to FL and I never got my chance to put hands on Salminus as I had hoped.

 

[Andrew_Murphy]

Thanks all for the kind words and encouragement, I truly appreciate it. A ton of research has gone into this acquisition, a lot more research has followed since, and continues when time allows. At this point I have read, re-read, and cross referenced every major paper on the genus and also combed through a few dozen papers where the genus is merely mentioned. Though I have come out with a probable answer to my original question "Are these fish S. brasiliensis?" I'm left with many many more than I had anticipated for such a well studied taxon. Currently, the two primary questions I have and intend to pursue are:

1. Are these animals genetically representative of a wild population or a derived product of aquaculture? There seems to be a degree of disparity in development and morphology, which varies source to source. This species has only been reported as commercially aquacultured in the past decade, point of origin can be misleading if we don't know where the original founding stock were harvested from or if the animals were hybridized(intentionally or not) with the the existing S. franciscanus. It is evident that this species has an immense amount of genetic diversity so it highly probable that some of that diversity is expressed morphologically, which leads into my next question.

2. Are there clear divergent populations or subspecies and where do they occur? The river systems in which these animals occur are of a profound scale and subject to seasonal extremes and anthropogenic disruption(ranging from habitat destruction to introduction of alien sp.); accurately tracking and accruing data for a migratory population over a large shifting aquatic ecosystem is PhD work, not something I am able to pursue at the moment. That being said there is research being done on individual Salminus populations, however (as far as I am aware) there is no "big picture" research comparing development, morphology, life history, etc. of these populations. There are also mentions in many SA check-lists of large Salminus sp. in the Amazon River Basin and even the Orinoco(!), these reports open up a whole other can of worms that I can barely fathom but to keep it simple I'll take those reports as introductions or mistaken IDs.

So in summary I am just as confused as you folks but hope that, together, we can paint a clearer picture of the genus.

moe214: Re: scale counts. Morphometric standard for scale counts are dorsal origin to lateral line, following the natural progression of the scales, however with Characins in particular there is a lot of variability in counts from one animal to another. I think every formal description I have seen of the order is ranged. If only it were as easy as Arowana...haha

Chicxulub: I would be honored to contribute to your guide. While I am not yet 100% confident in generating diagnostics, I would say the addition of utilizing dentition as a diagnostic marker would be helpful, if only for sub-adult/adult animals. We have a Brazilian national working at my facility who is connecting me with staff at Sao Paulo University; where most of the holotypes of Salminus are found. I'm hoping to either get eyes on these specimens or pictures, while of course asking(and hopefully getting answers) to many of the questions we all have. When time allows I'll trawl through my folder of papers on the genus and see if I can digest it into something accessible but definitive.

Full disclosure: Salminus research is unfortunately taking a back seat to some Upper Rio Negro Corydoras work I'm in the middle of but that should settle down within the next month. If only my systems would take care of themselves haha

Cheers,
Andrew

 

[DB junkie]

I wish I found it half as interesting as I do frustrating.......

As someone who has "supposedly" had both species sure seemed to me to be pretty easy to tell them apart, yet none of the proposed "Brassies" looked like the one I had. Even the one that was supposedly from the same batch looked different. Guess "Robert" must have just been an oddball?

I do believe he's still on ice if it would be of any help to anyone I'll gladly send this fish cicle.....

 

[Chicxulub]

I wish I found it half as interesting as I do frustrating.......

As someone who has "supposedly" had both species sure seemed to me to be pretty easy to tell them apart, yet none of the proposed "Brassies" looked like the one I had. Even the one that was supposedly from the same batch looked different. Guess "Robert" must have just been an oddball?

I do believe he's still on ice if it would be of any help to anyone I'll gladly send this fish cicle.....

It could be a matter of locality. Robert was from Argentina, the other dorados that we see are from Brazil. If they were the same species, it could be as simple as locality differences. Honestly though, the Argentine fish are quite distinct morphologically from the Brazilian ones, regardless of inconsistent LL counts.

If a comprehensive genetic haplotype survey was done on Salminus as was done on Hydrocynus, we'd see a few new, species or subspecies level genetic populations discovered. In that same vein, we have to keep in mind that there are currently at least five undescribed Hydrocynus lineages out there, one of which is almost certainly in the hobby being called the wrong thing (but the hobby is confused enough, so I don't talk about that lmao). If we did a similar survey of Salminus, I'd wager almost anything it would turn up similar results.

 

[headbanger_jib]

The ones with me are from Brasil, but their mouths are quite pointy