P. pangasius vs. P. hypothalamus

[necrocanis]

Hey guys. I bought two sets of Pangasius cats and was having a bit of a friendly debate on species with a friend who is a regular here. I decided to post up some pics and see what you guys had to say. From what I can gather from info on here and other sites I have two distinct sets of pangs. One species is ID shark Pangasius hypothalamus, and the other is Pangasius pangasius. I bought them from the same store where they are both regularly sold. One is sold as irridescent shark, and the other is sold as pangasius shark. When I did a little research I came up with my conclusion. I've been told by my friend that maybe it's sexual dimorphism. I'm curious to see what you guys think. So without delay here are the pics. I've noticed in pics on the web and from my fish that what I consider P. pangasius has a shorter snout, and larger stomach. Coloration seems the same though, but the physical differences strike me instantly. Maybe I'm crazy though lol. I've included pics of both seperate, and one of them together. Let me know if you guys would like more.

[MatsP]

I believe both of the species are commonly farmed as food-fish, so there may well be specimens of both in the trade.

Pangasius hypophthalmus

data-sheet says that males are dimorphic.

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Mats

[Shovelnose]

Hello necrocanis,

Looka like your gonna have to rent a lake soon. When you say Stone Catfish are you referring to Hara Jerdonis????

[necrocanis]

It's a pretty vague dimorphic description, and it says it's unknown what size it becomes evident. The ones I think are ID sharks have pretty much looked the same since they were small, and the others also. That's from about 1.5" til the ID shark's now 9", and 8". The pangs are 6", and 5". They all school together, but then again my smallest lima schools with them also.

As for the stonecat, not really what I want to discuss here, but it's a Noturus flavus, and was recently given to a friend. I caught it while fishing here in Montana. Close to a state record, but I gut hooked it and felt it my obligation to keep it and doctor it up. After I had it for 3 months and it was eating like a pig I passed it on to a friend who had smaller fish to keep it with.

Was really hoping to get the opinion of Heok Hee Ng. on the Pangasius issue. I've been told he's the foremost expert on Asian catfish. I appreciate everyone's insight though.

[Richard B]

Hypothalamus is sold in the trade as both pangasius shark & irridescent shark & is the most commonly imported species. The bottom fish does look to have a blunt snout compared to the other fish but otherwise they seem quite similar & i think someone like Silurus needs to comment to give you a definitive ID.

[necrocanis]

Oh, one thing to mention is that the P. hypothalamus has a hump above it's head on everyone I've seen in the stores, and the P. pangasius has just a smooth head. This is from a very small size, and I doubt that anyone is seperating out males and females to the degree that they are sold seperately in my lfs. There will be as many as 35 or more in each tank. All the ones labeled ID shark have the hump and are more slender, and all the ones labeled Pangasius sharks have the shorter snout without hump, and fuller body. The owner claims that's how they come in. Not sure as I was suprised to see anything other than ID sharks in a lfs here in Montana. We don't really see that many catfish here. I've had to fly in all the ones I have, and I'm like the local catfish rescue center basically. Currently building a 4000 gal, a 200 gal, and after these are complete I'm starting on both a 500 gal, and another 1800 gal tank. If I had a tropical lake with a viewing window at one end I'd be the happiest man alive!

[necrocanis]

Hypothalamus is sold in the trade as both pangasius shark & irridescent shark & is the most commonly imported species. The bottom fish does look to have a blunt snout compared to the other fish but otherwise they seem quite similar & i think someone like Silurus needs to comment to give you a definitive ID.

Yeah, I think that's the main confusion. I just don't want to get my hopes up of having two species and I only really have one. I love them the same no matter though. I've noticed that many Pangasius species look very similar at a small size. If nothing else I'll have to grow these out huge so I can be certain. Silurus is the guy I'm look for an answer from, but I'm not in a rush. The fish will still be there tomorrow lol. Eating like pigs and growing.

[Silurus]

Do you have a better picture of the head of the short-snouted fish?

[necrocanis]

I'll try to find one! brb.

[necrocanis]

These guys are much harder to photograph than the IDs. much faster, but here's a few more pics. Most of the pics of them are really blury, but I went through to try and find a few decent ones. Note the lack of hump right in front of the dorsal fin. All the ones I've seen in the LFS are like that, and if you look back at the pic of the ID shark it has the lump there. Just trying to make certain.

[Silurus]

My quick and dirty initial assessment is that they are both Pangasianodon hypophthalmus.

[necrocanis]

Hmmm, this is odd. Why would they get two fish of the same species in under different names from the same distributor, and why would the distributor go through the trouble of seperating out all the ones that look similar. Seems like it would take a while for fish that only costs $7.00. I'm still not 100% convinced they are the same species. Unless of course it is the sexual dimorphism, and they are seperating males and females and selling them under different names. The first time he got them in he had gotten them under the name imperial sharks. I told him I didn't think they were imperial sharks and when I looked at his order list he had both Irridescent sharks, and pangasius sharks from the same supplier. Very odd indeed. Non-the-less I will raise them out and see what kind of beauty I can get out of them!!

[MatsP]

Or the wholesaler/importer is buying fish under different names from different exporters, which really are the same species - and the wholesaler/importer simply don't know they are the same species....

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Mats

[wayne the pain]

Hi Cliff, i will sit on fence and say nothing, other than nothing would amaze me what exporters of fish will do to sell fish, ie tattooing, dying, mutations etc,so separating them "sexually", and selling as different sp wouldn't surprise me in the slightest.

[apistomaster]

It's a pretty vague dimorphic description, and it says it's unknown what size it becomes evident. The ones I think are ID sharks have pretty much looked the same since they were small, and the others also. That's from about 1.5" til the ID shark's now 9", and 8". The pangs are 6", and 5". They all school together, but then again my smallest lima schools with them also.

As for the stonecat, not really what I want to discuss here, but it's a Noturus flavus, and was recently given to a friend. I caught it while fishing here in Montana. Close to a state record, but I gut hooked it and felt it my obligation to keep it and doctor it up. After I had it for 3 months and it was eating like a pig I passed it on to a friend who had smaller fish to keep it with.

Was really hoping to get the opinion of Heok Hee Ng. on the Pangasius issue. I've been told he's the foremost expert on Asian catfish. I appreciate everyone's insight though.

The foul hooking of a madtom catfish has to be a first.

[featherback]

I don't know anything about the id in question, but I want to say, like Mats said before me, that they could very well just be from different stocks (different breeders/exporters). I've had the same situation with "Bala sharks", twice my lfs got shipments of obviously different looking fish. Although I fantasize about them being B. ambusticauda they are with 99% certainty inbred B. melanopterus from a different farm.

Generally, I assume that different breeders often produce slightly 'different forms' because they are not producing siblings, like most fish in one shipment from one breeder most likely are.

I think it is far fetched that they would separate males and females in Pangasius specie. If there were a profit to be made from selling both species it would be cheaper to offer both (or just sell the same fish as two species, which is not unheard of).

I hope you find they are different species ...or sexes!