pangasius hypalthalmus, iridescant shark Part2

[Silurus]

Dinyar,

The most commonly cultured <i>Pangasius</i> is <i>P. hypophthalmus</i> (which I have been told is now a <i>Pangasianodon</i> and not a <i>Pangasius</i>), which is the iridescent shark of the aquarium trade. In southern Vietnam, this species is cultured in floating cages in rivers and that is presumably what "basa" is.
However, <i>P. djambal</i> or <i>P. polyuranodon</i> are more commonly-cultured species in Indonesia (In Sumatra, I observed floating cage cultures of the the former species).
<i>Pangasius sanitwongsei</i> (you're right, it was my spelling error) is commonly referred to in the aquarium trade as a paroon shark (never as an iridescent shark).
The only other speices of <i>Pangasius</i> I have seen in the aquarium trade (though not frequently) is <i>P. larnaudii</i>, which is another gigantic species. The Indian exporters also bring <i>P. pangasius</i> into the trade, but I believe that this is also not common.
Besides <i>Pangasius</i> and <i>Pangasianodon</i> (now including <i>P. gigas</i> and <i>P. hypophthalmus</i>), the only other pangasiid genus is the exclusively molluscivorous <i>Helicophagus</i>.

[Silurus]

Dinyar,

Only one problem: where do you get the fish?!

Sorry, I was still thinking I was in Singapore when I wrote that. <i>Mystus bimaculatus</i> is not too rare an aquarium fish in Singapore. Heck, when I was in Sumatra, they were regularly catching thousands of these guys for export. Same thing with the false glass cats (<i>Pseudeutropius</i>). <i>Silurichthys</i> is a relative rarity, but I've seen it exported occasionally (market for it isn't very big, because they are a plain mottled brown and spend most of their time lying on their sides, unlike other small silurids).
I once set up a tank similar to that back in Singapore, using only fish I had caught from the wild (man, I wish I was back in Asia!)

Do you mean "peat in the gravel", Heok Hee, or "pure peat as substrate"? Wouldn't the latter create a huge mess? The stuff would float all over the place!

I forgot that aquarium peat floats. In their natural habitat, these fishes would be found in swamps and streams where the substrate is a fairly thick layer of peat. I have used peat as a substrate before, but I had to soak the stuff like crazy to make it sink. It also tended to clog the filters. So, maybe the best idea is to use it with gravel.
I wouldn't worry about low pH. In the blackwater areas, the average pH of the water is about 4.0, and it sometimes dips to 3.5! I had to be careful not to have any cuts or abrasions on me when I was fishing, otherwise, the water would really sting those wounds!

[Dinyar]

Life at pH 3.5!! Wow!! I knew the pH could drop pretty low in blackwater swamps, but never realized it could get THAT low! Do you see plant life in these swamps?

Thanks,
Dinyar

[Silurus]

What do you mean exactly by plant life? Above or below water?
Below water, the water is a rich brown color, kind of like very strong tea or cola, so there is too little light for underwater plant life. Besides, the peaty substrate is too unstable for anchorage. That said, I have sometimes seen sundews (cannot remember the genus) floating around in the swamps.
It's a different story above water. You get a regular rainforest (if the habitat is pristine) around you, with lots of giant dipterocarps.
Unfortunately, these peat swamp dipterocarps are the most valuable as hardwoods commercially, so they are usually the first to be targeted by logging companies, who will drain the swamp before logging (so that heavy vehicles can use logging trails cut through the peat swamp forest). You can imagine what this will do to the fish.

[jscoggs27]

errr.. has anyone else had any succsess at keeping iridescant sharks?

jason

[Dinyar]

What we are saying is "adult fish in an aquarium, NO!"

Dinyar

[jscoggs27]

ok. ok....
I get your point. sorry to have caused offence, I was curious to know peoples experiences problems with keeping this fish as they are very common here in the shops.

thanks
jason

[Dinyar]

sorry to have caused offence

No offence taken.

Besides Pangasius and Pangasianodon (now including P. gigas and P. hypophthalmus), the only other pangasiid genus is the exclusively molluscivorous Helicophagus.

I have a Chinese book entitled <Yulei Fenleixue> (Ichthyological Taxonomy) that lists a fish called "Hua Mang" (Chinese Pangasius), Sinopangasius semicultratus, Chang & Wu. It also says this is a marine fish. Is this possible? No species with a similar name is to be found on FB, but a Google search yields several hits that all turn out to refer to the same article on endangered freshwater fish in China (including a version of the article apparently authored by Sven Kullander).

Dinyar

[Silurus]

<i>Sinopangasius semicultratus</i> is considered a synonym of <i>Pangasius krempfi</i>, which is one of the few <i>Pangasius</i> species to undertake migrations along the Mekong River on the scale of those for giant pimelodids, as it is regularly found far out at sea in the Gulf of Thailand.

[coelacanth]

sorry to have caused offence,

Doubt there was any offence caused, it's good that you are interested and that you asked. You've touched on one of the real problems of the aquatic hobby. There are some Catfish which are simply totally unsuited for the home aquarium, and some that are too big even for most Public Aquaria.
All the Pangasius currently available in the aquatic trade fall into this category as far as I'm concerned. They are pelagic swimmers, unlike most other Catfish, and pose a set of demands pretty well unique in freshwater fish.
Unfortunately they are available very cheaply as youngsters, hence good profit margins, they are interesting to look at, hence easy sales, and they invariably die, hence repeat sales.
As a guide, and this is probably insufficent, they should have at least 20 times their own body length for swimming in at least one direction, and I would say at least 10 times their own body length in any direction. So, by the time that newly-purchased 3 inch 'Iridescent Shark' gets to be 1 foot long (less than a year under normal circumstances), the aquarist would be looking at an aquarium larger than the average garage. Then, bear in mind that this is a fish that is only one-third grown, and that the other species get even larger.
As far as I know I am the only Forum member who works in a (small) Public Aquarium. I get offered these things on a weekly basis, and there is nowhere for these fish to go.
Pete

[Jools]

Sorry guys, I attempted to split this topic into two but made a mistake. You now have 3 posts (2 for Pangasius) and the one on the "perfect set-up".

Sorry. but I haven't deleted anything!

Jools