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In my continuing quest to find tankmates for my argentinian Otocinclus flexilis, I found that Corydoras hastatus is a subtropical species found in Southern Brazil and Argentina. A search of the net for temperatures of its home waters suggest that winter temperatures may dip to 7 celsius (45F), while summer temperature may reach 40C! (104F!).

That would make it an ideal companion for my otos, who are just now in "late autumn", with temperatures in the 15C - 20C range (60 - 70F).

However, every care-sheet I find about hastatus recommends a year-round temperature of 24-26.

Does anyone have any input on hastatus ability (or inability) to handle low temperature?

Alternatively, any info you might have about their natural habitat would be intresting to me.

If you look at , you can see the coordinates for it's type locality, which is 2°38'S, 56°45'W. Map that, and you'll find it on a line between Manaus and Santarem in northern Brazil. Pretty close to the equator, and thus fairly stable year-round climate, I would think. [Although I have never been there, so I could be wrong - I was last time I gave weather predictions for somewhere...]

Unfortunately, the other "dwarf" species of Corydoras (habrosus and pygmaeus) also seem to be pretty close to the equator...

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Mats

MatsP wrote:If you look at

Corydoras hastatus

, you can see the coordinates for it's type locality, which is 2°38'S, 56°45'W. Map that, and you'll find it on a line between Manaus and Santarem in northern Brazil.

Yes, I saw that, but I suspect that's a mistake. If you go into Fishbase and plot all collection records of C. hastatus, you get a dense cluster of about 30 "spots" in southern Brazil/Northern Argentina, and that ONE "spot" in Manaus.

EDIT: I used GBIF's tool to map the data for the 81 C. hastatus in the GBIF collection database to Google Earth (each X is a capture locality):
http://mikes-machine.mine.nu/temp/fesk/ ... status.jpg

Personally I find the distribution implied by that plot unlikely.

Corydoras hastatus is found in one or two locations, but are common in the Rio Paraguay drainage in Brazil. The best temperature range for these Corys would be 22ºC to 25.5ºC (72ºF to 78ºF).

Ian

Coryman: for keeping I agree, but do you think they'd be able to handle "overwintering" for two months at 5-10C?

EDIT: Also, would you happen to know if there really are two distinct areas where they're found: Rio Guapore drainage and Rio Paraguay drainage? Any differences between the two populations?

In a word NO. If you want something that will tolerate those temperatures then you need to look at some of the species from Argentina, Southern Paraguay or South Eastern Brazil.

Ian

Ummm... did you look at the distribution plot I posted?

I wouldn't ask if it wasn't a species from southeastern brazil, paraguay, argentina.

I have looked at the plot and as far as I am aware C. hastatus are not found as far south in Paraguay as shown. There is also a form that has been found in Colombia, but there is a chance that these could be a new species or even a population that has developed from escapees from a fish farm.

As a side note, I believe this is something that is happening all the time and could be adding to the identification confusion, with species cropping up where they are not normally found.

The locations shown would indicate they should be tolerant of lower temperatures, but I would be very wary of letting then go below 16 or 17ºC.

Ian

OK. I'll use paleatus and sequester them at breeding time with a net or something.

As an aside, the implied distribution of C. hastatus is, I agree, extremely suspicious. Unless it is some sort of mix-up, I would suspect it is really two similar species.

Hi Mike and all, the thing is not so clear for me since i had no contact with the real hastatus from peru or brasil.
Argentinian especie is really similar and it´s the same that is in paraguay drainage and here is usually found in lagoons that in winter have a promedy of 10-12ºC water temperature and the fish are ok.
But i think will be hard find this fish from argentina or paraguay there, maybe in Germany...
C. macropterus it´s a nice especie, also c. undulatus and there are more than can tolerate low temperature, also few species of hypostomus and ancistrus.

Coryman: C. australis is a synonym of c. hastatus?

AGV,
I know about C. australis being a synonym of C. hastatus this was proven in 1980 bt Nijssen & Isbruecker. There are a couple of new species for the Misionies and Corrientes regions, one is similar to C. paleatus but this one has a long extended dorsal fin and is awaiting publication of the description.


The other species (C07) is a lot smaller but shows a similar extended dorsal fin and is called in the trade Corydoras sp "Misiones"


Both of these species prefer lower temperatures 13ºC to 18ºC.

Ian