2: the aquarium stream (Austria)

by Paul Veenvliet
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2: the aquarium stream (Austria)

Post by illustrator » Sun Sep 21, 2008 3:03 pm

There's not much news about my new aquarium: it's not delivered yet.

In stread I post some pictures which I made last year in the »aquarium stream«, a small thermal stream in Austria, where numerous aquarium fish and plants have been introduced. At least 4 species reproduce in the stream (Amatitlania nigrofasciata, Hemichromis guttatus, platy x swordtail hybrids and Ancistrus »sp.3«). Depending on the moment you can see single individuals of almost any possible other aquarium fish. Also native fish are present. This means that there's a high risk of transmission of "aquarium-diseases" to native fish. Downstream the the thermal stream joins a very cold one, below this point, no tropical fish occur.
21_sept.JPG
The stream
21_sept_(1).jpg
Vegetation (as if you look in an aquarium from above …)
21_sept_(2).JPG
Feral convicts (and a Hemichromis), underwaterphoto – yes, that's a food-tablet between the fish
21_sept_(3).jpg
Convict and a lost barb (note the damaged tail of the barb: this is common in all fish in the stream: Hemichromis are fin-eaters!)
21_sept_(4).jpg
Hemichromis guttatus pair in the stream, if you look very carefully, some of their young are visible
21_sept_(5).jpg
Native chub in the stream (Squalius cephalus)
Last edited by illustrator on Wed Jan 21, 2009 6:57 am, edited 4 times in total.

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Grummie2
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Re: 2: impressions of the aquarium stream (in Austria!)

Post by Grummie2 » Sun Sep 21, 2008 5:43 pm

WOW!, first time I've heard of this ! How long is the stream 'tropical' ? It must still be difficult to maintain it's temperature in winter?
Graham

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Re: 2: impressions of the aquarium stream (in Austria!)

Post by Lee Nuttall » Sun Sep 21, 2008 5:50 pm

Wow, thats just crazy, i would never of known, thanks for sharing.

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Re: 2: impressions of the aquarium stream (in Austria!)

Post by Mack Emmons » Sun Sep 21, 2008 10:47 pm

Interesting, thanks for sharing.

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Re: 2: impressions of the aquarium stream (in Austria!)

Post by illustrator » Mon Sep 22, 2008 2:22 am

The stream is fed by a hot spring, the temperature is 25 degrees centigrade (= optimal tropical aquarium temperature) throughout the year. This is known for a long time, part of the warm water is used by a luxurious spa (health resort). For some decades there are tropical fish in the stream: in the past there were guppies and mosquito fish. These apparently went extinct since Hemichromis guttatus established a very large population. The stretch with tropical fish is little more than 1 km long, after that the stream joins a very cold one. Native fish swim of several species in and of the warm stream.

Even more amazing: there is are least two more streams like this in Europe, one in Slovenia (with nile-tilapia) and one in Hungary (with guppies and "Herotilapia" multispinosa) - and a warm pond in Slovenia with tropical lotus flowers. I'd love to know of more similar places, would be nice to make an overview and see if similar fish species have a higher chance of becoming established.

I have the feeling that livebearers, pleco's and cichlids have better chance to establish populations, because they reproduce better in aquariums (more surpluss and not "ust single individuals" being released) and because of their parental care (after all, also livebearing can be seen as a form of parental care) ...

This would imply that livebearers, pleco's and cichlids are also the most dangerous potential "aquarium" invasive species in countries with a warm climate.

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Re: 2: impressions of the aquarium stream (in Austria!)

Post by Grummie2 » Mon Sep 22, 2008 3:03 am

Looking at the species released you can also tell to some extent the 'level' of aquarists that are responsible. Most of the fish seen are 'starter' fish, so are probably released by children or new aquarists that have not had success with their hobby. I know its wrong....but I'd want to put something a little more interesting in there !!!!!!!!!
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Re: 2: impressions of the aquarium stream (in Austria!)

Post by illustrator » Mon Sep 22, 2008 3:23 am

True, and there is also at least one austrian aquariukeeper that keeps convicts "from the stream" and keeps releasing the ofspring back into the stream "because they would end as fishfood otherwise" ... (According to his postings on an Austrian forum.)

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one or two Hemichromis?

Post by illustrator » Wed Oct 08, 2008 8:31 am

According to literature there are two Hemichromis species in the aquarium stream: H. guttatus (variously identified: this is the dentification of J. Freyhof) and H. fasciatus. I never saw H. fasciatus in this stream myself. However, I am not so certain if all "normal" H. guttatus are really the same species. For a while I had some young ones in my aquarium and made these pictures:
hemichromis1.jpg
Individual with very little colouration in anal- and tail fin
hemichromis2.jpg
Individual with a lot more colouration in anal- and tail fin, the larger and more pronounced blue spots on the body can be caused by a general larger size of this fish. However, I observed the difference in fin-colouration in ish of all sizes ...

At first thought that these are female and male of the same species, but when you look at the photo I posted earlier, it is clear that this pair is composed of two "colourfull" individuals. So what do you think? Two varieties or two species? And which one is the real H . guttatus and what would the other one be?
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Re: one or two Hemichromis?

Post by Bojan Dolenc » Fri Oct 17, 2008 10:10 am

illustrator wrote: So what do you think? Two varieties or two species? And which one is the real H . guttatus and what would the other one be?
That is really hard to say. Genus Hemichromis is the most difficult one to accurately identify to species level. The fact of the mattter is that we really lack an absolutely satisfactory knowledge of the systematics of the genus. Sorry, I didn`t help you, but so it is :( In my opinion they are the same species.
Change in habit, producing change of function, is the main cause of the production of change in living structure. F. Wood Jones (1953) Trends of life

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7: stream re-visited

Post by illustrator » Wed Nov 12, 2008 9:55 am

I have re-visited the stream yesterday, in order to catch an »unrelated« male convict for my new aquarium. A few impressions:
stream.jpg
(note the Cryptocoryne-plants in the stream)
cray.jpg
My big worry: a species which is abundant in the stream, but which stands cold water and transmits a lethal disease to related native species (florida red crayfish, which often carries crayfish plague, a fungus-disease which eradicates populations of native crayfish – photo taken in the Austrian stream).
aust1.jpg
A female con. Most individuals in the stream have a fairly regular stripe-pattern, this one is a bit »off« on one side. The intensive orange colour is typical for many females in the feral population. Parts of the tail fin are bitten of by Hemichromis.
aust2.jpg
The small male (3.5 cm) that went home with me.

to be continued ...
Last edited by illustrator on Wed Jan 28, 2009 5:27 am, edited 3 times in total.

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Re: 7: stream re-visited

Post by illustrator » Thu Nov 13, 2008 6:15 am

Already last year I noticed Ancistrus "sp3" in the stream. Since then I have two stream-caught females in my aquarium, together with a petshop-male, and since a week or so a whole bunch of offspring – which I moved to another aquarium. Not only in my aquarium are they doing well: also in the stream numbers are increasing: I now caught about 10 in no time. All females and youngsters, apparently both in the stream and in my aquarium males lead a hidden life.
cat.jpg
But these are not the only catfish in the stream. I was searching for some small fish (more about that later …) when there was a sudden, very large movement in the dense vegetation in front of me. Moments later a 80 cm wels cafish (Silurus glanis) swam away in the shallow water, creating a bow-wave where it went. This was my frst encounter with this impressive species in nature. In fact, it was a small one: this is the largest European freshwater fish and they commonly reach 1.5 meter and a lot more according to fishermen. One more native species to ad to the list of observations in the »aquarium stream«.

to be continued ...
Last edited by illustrator on Wed Jan 28, 2009 5:28 am, edited 1 time in total.

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Re: 7: stream re-visited

Post by Grummie2 » Thu Nov 13, 2008 7:24 am

WOW, what a selection of species there is !! That wels should keep the numbers down a bit tho' !!
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Re: 7: stream re-visited

Post by illustrator » Fri Nov 14, 2008 4:58 am

When I first visited the stream, I caught 2 wagtail platy's and a red swordtail-platy hybrid. I had no real place for them and released them back into the stream. I later regretted this, but at my second visit (last year) I didn't cach any - even though briefly saw two platy's swimming between dense vegetation. So now I had "catching platy's" as a main goal. I was there or about 2.5 hours, and only in the last 5 minutes ... at last I had two platy's in the net. I still believe there is a small population there, but they remain rather elusive ... Photographing is also difficult, because their scales reflect the flashlight like mirrors. They lost some scales in the net, but these will grow back. Anyway, I have these two now at home, and they're even a male and a female. Not exactly wagtail-hybrids, but this is very likely the same variant which I briefly saw last year. I think that those wagtails were recent releases rather than representatives of a population.
platy.jpg
platy.jpg (60.53 KiB) Viewed 10023 times
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Re: 7: stream re-visited

Post by Lisachromis » Fri Nov 14, 2008 9:11 am

Amazing, you can visit other countries without leaving home! Definitely someone getting rid of their aquarium fish the wrong way..... That platy is actually quite good looking. I like the blue iridescence.

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Re: 7: stream re-visited

Post by illustrator » Fri Nov 14, 2008 9:33 am

There's an ongoing history of repeated introductions for some decades there. For now it looks like only 4 fish species have established populations. And, yes, I like the platy too :D

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Re: 2: the aquarium stream (Austria)

Post by illustrator » Tue Dec 23, 2008 5:37 am

Just a short notice: I just saw the first few young of my pair of "Austrian platy's". I hope they survive because I would like to see how much variation there is in colouration. Less variation = indication of a longer established strain (either in an aquarium or in the stream).

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Re: 7: stream re-visited

Post by PeterUK » Sat Dec 27, 2008 5:54 pm

illustrator wrote: Moments later a 80 cm wels cafish (Silurus glanis) ............ In fact, it was a small one: this is the largest European freshwater fish and they commonly reach 1.5 meter and a lot more according to fishermen.
ACCORDING !!!!...... :lol: :lol:

http://www.wwwserv.co.uk/ccg/gallerypicsspain.htm

especially towards the bottom of the page :shock:
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I laugh at them because they are all the same.


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Re: 2: the aquarium stream (Austria)

Post by illustrator » Tue Jan 13, 2009 5:17 am

An incomplete list of aquarium plants, which grow in the Austrian stream:

Riccia fluitans (local)
Hygrophila polysperma (few; local)
Shinnersia rivularis (abundant)
Vallisneria spiralis (abundant)
Cryptocoryne balansae (few individual plants, have to search for it)
Cryptocoryne wendtii (abundant in the part where few aquarists come, elsewere more rare: aquarium keepers keep taking these plants from the stream)
Pistia stratiotes (dependent on season: abundant in summer)
plantje.jpg
Note the not-so-known-emerse-form of Shinnersia rivularis.
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Re: one or two Hemichromis?

Post by illustrator » Wed Jan 21, 2009 7:00 am

Bojan Dolenc wrote:
illustrator wrote: So what do you think? Two varieties or two species? And which one is the real H . guttatus and what would the other one be?
That is really hard to say. Genus Hemichromis is the most difficult one to accurately identify to species level. The fact of the mattter is that we really lack an absolutely satisfactory knowledge of the systematics of the genus. Sorry, I didn`t help you, but so it is :( In my opinion they are the same species.
I think that you are right: I believe that I have seen a mixed pair in the stream last November.

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Re: 2: the aquarium stream (Austria)

Post by RCorreia » Thu Mar 19, 2009 6:32 am

I have heard about feral populations of platys, swordtails, and convicts, in Austria, Chzech Republic, etc.. But I didn´t know that they were localized in thermal springs...fantastic!!!!!! They have superb colours.

In winter, when it snows, the stream can mantain that temperature?


best regards,

Rui Correia

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