My Brachyplatystoma filamentosum (Disscussion)

[GiantFishKeeper101]

Quick Update

Must've grow 3" in a month. That's a coincidence growth spurt to my wels catfish. Both have exponential growth rate.

 

[GiantFishKeeper101]

After thorough investigation both Brazil & Peru between rivers (nanay, araguaia, rio negro, etc), I've concluded that there's no difference between them. Both piraiba do comes with lighter & darker colors. Spots varied between individuals, Peru having less spots & Brazil having more spots. Both endup having the same color when fully grown, light blue/grey.

The only difference between the rivers are Rio Negro blackwater tributary, piraiba caught there having darker colors but specimen caught only around 3-4'. Meaning juveniles feeding there as the 2 rivers meet up, brings a lot of food.

But there's a few difference, to my eye. Some specimen have pointed snout & some specimen have slightly curved snout. Theoretically, difference between genders as do the redtail catfish.

But there's definitely differences between Suriname & Brazil. Brazil have shorter shoulders & gradually inclined, robust body. Suriname have rounded & longer shoulders, streamline torso.

All these are just theory, investigation only through photos. Its not wrong and its not right either, but it is usable.

 

[GiantFishKeeper101]

A few weeks back, I given my "research" to a catfish expert. He sees it as an interesting topic. So he posed the question to Lundberg (who described the B. capapretum) at the Catfish Study Group convention.

If it indeed to be truly reliable, he's going to discuss this topic to his colleagues in Manaus. So, we'll wait for his new study. See the outcome or perhaps, new subspecies.

 

[thebiggerthebetter]

After thorough investigation both Brazil & Peru between rivers (nanay, araguaia, rio negro, etc), I've concluded that there's no difference between them. Both piraiba do comes with lighter & darker colors. Spots varied between individuals, Peru having less spots & Brazil having more spots. Both endup having the same color when fully grown, light blue/grey.

The only difference between the rivers are Rio Negro blackwater tributary, piraiba caught there having darker colors but specimen caught only around 3-4'. Meaning juveniles feeding there as the 2 rivers meet up, brings a lot of food.

But there's a few difference, to my eye. Some specimen have pointed snout & some specimen have slightly curved snout. Theoretically, difference between genders as do the redtail catfish.

But there's definitely differences between Suriname & Brazil. Brazil have shorter shoulders & gradually inclined, robust body. Suriname have rounded & longer shoulders, streamline torso.

All these are just theory, investigation only through photos. Its not wrong and its not right either, but it is usable.

It'd be nice to have this plus backed up with the photos, based on which you are making your tentative conclusions, in the Piraiba ID nuances thread.

I also suspect / realize that when you say "curved snout" or "snout is starting to curve" you mean not that the tip of the upper jaw curves down (which was what I thought you had been saying for a long time... while I have been failing to see it) but you mean that the sides of the upper jaw curve down making the snout more round and less flat in the "across the snout" dimension, not the "along the snout" dimension

If I am right, perhaps this could be clarified in your statements in the said thread as well because otherwise, it is ambiguous.

Also, I'd probably not trust the base color of any fish for an ID unless there are many photos and videos available of fish in calm state and settings. Landed fish is known to exhibit colors that may not represent it when it is in its normal state. Moreover, color depends heavily on the mood, diet, substrate, turbidity, time of year and time of day, gender, etc. and can vary widely. I'd use the base color as the last and the least reliable trait.

I also am not sure what you mean when you say "shoulders". Perhaps you can point it out using your drawings.

You're a good artist BTW.

 

[GiantFishKeeper101]

It'd be nice to have this plus backed up with the photos, based on which you are making your tentative conclusions, in the Piraiba ID nuances thread.

I also suspect / realize that when you say "curved snout" or "snout is starting to curve" you mean not that the tip of the upper jaw curves down (which was what I thought you had been saying for a long time... while I have been failing to see it) but you mean that the sides of the upper jaw curve down making the snout more round and less flat in the "across the snout" dimension, not the "along the snout" dimension

If I am right, perhaps this could be clarified in your statements in the said thread as well because otherwise, it is ambiguous.

Also, I'd probably not trust the base color of any fish for an ID unless there are many photos and videos available of fish in calm state and settings. Landed fish is known to exhibit colors that may not represent it when it is in its normal state. Moreover, color depends heavily on the mood, diet, substrate, turbidity, time of year and time of day, gender, etc. and can vary widely. I'd use the base color as the last and the least reliable trait.

I also am not sure what you mean when you say "shoulders". Perhaps you can point it out using your drawings.

You're a good artist BTW.

There's too much photos that I refered to. Googles & instagram mostly. Instagram photos have complete info where the beasts been caught. That's my number 1 source.

Sorry for making confusing statements. Some proper english words eluded me. Everything you need to know I've already compiled below comments. The specimen used are my 8" Peru/Brazil and my friend 8" Suriname. By the way, thanks for your compliment. Sadly my talent won't get me anywhere, so I abandoned it.

 

[GiantFishKeeper101]

DEFINITIVE DIFFERENCES BETWEEN BRAZIL/PERU & SURINAME

Specimen used around 8". These characteristics will change when reaching adult (refer bottom pictures)

The dark piraiba: Brazil/Peru
The light piraiba: Suriname

Snout



Slight curvature on S snout tip, to compare to B pointed snout. This curvature are not from self inflicted damage.

Eye



S have popping eye. The eyes are protruding than the level of the upper skull.

Shoulders



This will make most confuse of what actually meant by shoulders. The muscular part between the head & dorsal spine. S have bulging & rounded shoulders, B have gradually smooth shoulder.

Head Length & Shape (nose tip to dorsal)



S have slightly longer heads. I have no complete specimen to compare, so theoretically, B have much deeper torso. So it gives the impression of B having shorter heads.

Body Type



B having robust body while S have much skinnier body type. Look at the circle part to see the difference.

Adult Photos



These are photos of larger specimen, top being Brazil and bottom being Suriname. Try to use info I've given at the top to compare between the 2, surely you can see the differences.

 

[thebiggerthebetter]

Great, wonderful effort. Thank you!

In the big guys, I think I see the snout, the head length, and the body robustness (not at the dorsal but past dorsal) differences.

I see no difference in the eyes.

In the shoulders I see an opposite difference to what you proposed - B appears to exhibit bulging muscular form. I think I see the same shoulder difference in the small guys, which makes me think what you proposed contains a typo... but like you said, it may be tough to see or subjective. The lighting, the color, the angle, etc. may bring it out or hide it.

The "shoulders" is where catfish store their reserves anyway. So this difference may have nothing to do with their DNA difference but how well fed they have been at the moment of the photographing. This trait would become more reliable if seen over many specimen, which, if I understand you correctly, you claim to have observed in Google and Instagram photos.

 

[Troy1015]

GiantFishKeeper101 great write up.

 

[GiantFishKeeper101]

thebiggerthebetter yeah, forgot to mention, difference in eyes only visible in juveniles

Located another Piraiba, supposedly Suriname after a lot of observation. Have my doubts, quite skinny, hard to properly id. But hope I'm right. Still in seller's hand, will be arriving tomorrow or the next day

 

[GiantFishKeeper101]

Now this are true Suriname. Success.

thebiggerthebetter there's another difference I totally miss. See the spots on the photo, they are evenly gap & actually the same size. So, that's one of the signatures.