2: the aquarium stream (Austria)

[illustrator]

The stream maintains a very constant temperature all year. In winter it looks quite funny: above water plants are frozen when under water there is a lush vegegation of Vallisneria and -in some parts- Cryptocoryne.

Please can you mail me what the location in Czech republic is? I now oof this one in Austria and one in Hungary, as well as a possible site at an industry zone in Italy (for wich i don't now details yet), but I haven't heard about a similar place in Czech republic. I am very interested to find out which species are there.

[RCorreia]

I dont know the locality exactly, and I cant find many references to it http://www.fishbase.org/Introductions/FishIntroSummary.cfm?ID=3231&genusname=Xiphophorus&speciesname=hellerii&stockcode=3427&vperiod=unknown&vc_code_to=203&vFrom=Unknown

The other locations, are also hot thermal springs?

Have you ever measured the temperature, that the exotic fish species tolerate outside the 24ºC area??? do they live outside that area of the stream? not even in summer?

best regards,

Rui Correia

[illustrator]

I will try to answer your questons in a bit more detail after my next visit to the stream, but the stream is joined by a very cold other stream. At this point there is a very sharp temperature-drop.

[illustrator]

Last friday I measured the temperature in the stream at several locations. I found the following:

- close to the spring: 26'C
- downstream, close to the confluence with a cold side-stream: 23'C
- temperature of the side-stream: 7'C
- some 30 meter downstream of the confluence (water of both streams completely mixed) 12'C

For some distance after the confluence there is a funny situation with Vallisneria and Crypocoryne along the left bank and Fontinalis antipyretica, a cold-water moss, along the right bank. In this stretch I could not find any tropical fish. The coldest point with Cryptocoryne was about 14'C.

More about my new observations later...

[illustrator]

OK, finally some more on my latest visit to the stream (24 April).

The weather was a bit grey, but OK for observing fish. Off and on there were a few drops of rain. The water level in the stream was maybe 25 cm higher than I remember from before, but the temperature was similar. Overall the vegetation has grown more dense, especially the aquarium plants now cover at least 70% of the stream bottom. Even though it's a jogging/dogwalking/horseriding area there were few people around, probably because of the weather. The most surprising finding was a little bittern, a very rare bird which I had never seen before in real life. I suspect that this bird was on migration and it does not usually live around this small stream.

Green frogs were off and on calling along the stream. I caught 3, which were all lake frogs (Pelophylax ridibundus). In the stream, I found both eggs and 3 cm long tadpoles of this species. Maybe I should note that identification of European green frogs is not easy: in central Europe there are 2 species and a bunch of hybrid forms (called "green frog" or "edible frog" - Pelophylax kl. esculentus - ) that can look similar to the parental species. With adult frogs in hands I am fairly confident about identification, and in this case the calls confirmed which species is present along the stream - it is entirely possible that some hybrids are also present, but I did not see/hear any of these.

The stream in April: rather "atmosphery".

[illustrator]

I observed the usual mix of native and tropical fish species:

* native
chub (Squalius cephalus) - abundant
barb (Barbus barbus) - school of adults near the confluence with the cold stream
silver crucian carp (Carassius gibelio) - a few adults throughout the stream

* tropical
jewel cichlid (Hemichomis guttatus) - abundant, many pairs with young and many young hiding between plants
convict cichlid (Amatitlania sp. ) - common, quite some young hiding between plants
bristlenose catfish (Ancistrus "sp3") - common, many young underneath pieces of wood and between dense plants

jewel cichlid in full breeding colours

I also found a few other fish, which are very likely recent releaces that won't survive very long in a stream with a dense population of jewel cichlids. It is again very clear that there are regular releases of aquarium fish, but very few species manage to establish reproducing populations.

a tetra which has lost it's tail to the cichlids (these Hemichromis are fin-eaters!)

I caught 2 female and 2 male guppies: one of the males missed most of it's tail. They swam together with 2 small platies, about the platies I'll post more in the separate topic.

... and even a single apple snail hiding between dense plants

[illustrator]

I also have to update the plant list. This is partly because I have learned more about plant identification and partly because some species have become more abundant and easier to find. So here's the new list:

Riccia fluitans (small quantities throughout the warmwater part of the stream)

Hygrophila polysperma (abundant in the upper part of the stream, clearly in more shadowy places than Shinnersia)

Shinnersia rivularis (abundant, mainly in the upper part of the stream)

Ludwigia repens (few clumps along the shore)

Rorippa nasturtium-aquaticum (a native plant, growing in small quantities between the tropical species)

Vallisneria spiralis (abundant)

Lagarosiphon major (few individual plants between other species, but spread out through the whole warmwater part of the stream)

Limnophila sessiliflora (few branches in clumps of other plants)

Cryptocoryne balansae (few individual plants, still growing in exactly the same spot where I found them before)

Cryptocoryne wendtii (abundant in the part where few aquarists come, elsewere more rare: aquarium keepers keep taking these plants from the stream)

Cryptocoryne usteriana (some large clumps in the relatively cool part of the stream, just below the confluence)

Pistia stratiotes (dependent on season: abundant in summer)

Hygrophila polysperma growing in dense clumps and sticking out above the water. I took a few branches from this clump to see if it's really the same as the underwater form which i took before from the stream: it is.

Ludwigia repens creeping up on the shore

Cryptocoryne wendtii in a strong current

Vallisneria spiralis was full flowering: clearly all are female plants.

[illustrator]

Impressions from a flash-visit to the stream, today:

It was freezing and some snow was present on the banks. Water lettuce plants were very small (like under an aquarium cover) but healthy and unfrozen.

I noticed a few "new fish", but photographing was difficult because of the foggy conditions. Looks like this is an OB-morph of some Malawi cichlid.

Clearly another cichlid, but which species? Any suggestions?

Seen, but not photographed: a leucistic (orange) chinese algae eater (Gyrinocheilus aymonieri), about 25 giebel carp (Carassius gibelio) and a roach (Rutilus rutilus, this is a native species). And of course many jewel- and convict cichlids as well as stunted chubs of various sizes.

[RCorreia]

On the last photo it seems to be Pseudotropheus crabo.

[armac]

It would appear that people continue to "seed" the river with fishes. I know that the situation is not good for the natives, but it is really beautiful, the contrast with the snow is amazing.

As an aside I guess with the cold water stream there, it really barricades the tropicals into a defined area, no chance to move any further. Once again, that is very picturesque.

Please continue updating

[illustrator]

A small addition about a plant:
Before I listed Cryptocoryne usteriana as growing in the stream. I am now growing these crypto's from the stream in my aquarium and after some time they become indistinguishable from C. spiralis var. balansae "green". So the identification has to be corrected. Remarkable is that in the stream they develop underwater leaves of at least 4 cm broad, while in the aquarium they are only about 1.5 cm broad.

[Bojan Dolenc]

Paul, that is very interesting!

[illustrator]

21 December 2010

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Pterygoplichthys gibbiceps, 40 cm

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I re-visited the stream yesterday, with the idea to make underwater photographs of plants (especially Cryptocoryne) and habitats, as inspiration for aquarium design. The "usual fish" were all still there: convict and jewel cichlids, bristlenose catfish, chub. Additions were a big "pleco" and a common carp. Between the chub I saw a single rud, I saw no other fish species. This was the first time that I have not been fishing in the stream, which partly explains the low number of species seen. Fish numbers were high, water level average. Plants have grown somewhat more dense than before. I'll upload more pictures in separate messages.

[illustrator]

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Same picture as above, with part made lighter: note the small jewel cichlid hiding here!

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[illustrator]

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Note that a convict cichlid found a nesting blace between a piece of wood and a beerbottle

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[Piotr Koba]

I don't know whether laugh or cry. Because stream looks very healthy, with that clear water and nice plants. However, they should live elsewhere. How do the native species together with the "feral" populations. As I see, Hemichromis sp. is very numerous there.

All in all, a very interesting topic.

[illustrator]

Jewel cichlids are numerous, but not at every part of the stream as numerous as on the picture. I took this picture in a open water place of a few square meter, surrounded by dense Vallisneria. Here I could photograph the fish, because elsewere they had more room and swam away. Also, the concentration of cichlids was much higher than elsewere in the stream. I would say that elsewere there is maybe 1 jewel cichlid and 1 chub for each square meter of stream (which is still a lot of fish ...). Also densities differ with regards to where in the stream you are: the warmest part upstream has clearly fewer fish. And after the confluence with the coldwater stream, you see no fish at all (neither tropical not native species).

As far as I have seen, no native fish are breeding in this stream. Chub are numerous, some in excellent condition, others a bit skinny (similar to "normal" small streams with chub). Some chub miss pieces of tail fin because of the jewel cichlids. Other native fish are probably not permanently present: each visit I see different species in different numbers. Chub are more shy than cichlids and therefore more difficult to photograph.

Not the best picture because of mudd stirring up, but here's a juvenile chub swimming between the cichlids.

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[illustrator]

What I really visited the stream for this time, was to photograph the underwater landscape. How these plants grow in "halfway nature" (at least when not planted by someone), how stones and branches combine with substrate and plants ... So, for inspiration of aquarium keepers No fish on these pictures.

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How the heck do you make a background of mud in an aquarium, with plants growing in this mud-background?

[Adrian Indermaur]

Hy,

I`m loving storys like this...! Maybe I read over it, but may I ask where the stream is located ? And any others that you know ?

Thanks in advance and happy holidays

Greets Adrian

[illustrator]

The stream is the Maibachl in Villach, at Warmbad. With that you should be able to locate it.