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Discussion Starter · #1 · (Edited)
While researching on guppy cold tolerance I came across this research article/record, thought it was somewhat interesting.

Abstract
"Artificially heated water bodies represent unusual habitats in temperate regions and form a refuge for exceptional fish communities. The Gillbach, a tributary of the river Erft in Germany, receives thermally polluted cooling water from a power plant. Here, we present data on the composition of the fish community in the Gillbach and found a high abundance of invasive species from all over the world, mostly introduced by releases from home aquaria. We found a species composition that is dominated by invasive species containing the same species as 15 years ago. We focused on guppies (Poecilia reticulata) and determined population size using the mark-recapture method. Furthermore, we investigated the lower thermal tolerance limit (C Tmin) to determine if Gillbach guppies have already adapted to colder conditions compared to ornamental and Venezuelan wild type fish. We caught guppies of all sizes, and densities of 3.6 adult guppies per square meter were comparable to densities found in their natural distribution area, pointing toward a self-sustaining population in the Gillbach. The C Tmin varied between populations and was significantly lower in ornamental and Gillbach guppies compared to guppies from Venezuela. Despite differences in C Tmin and their well-known potential to adapt to new environments, guppies originally stem from the tropics, and a further spread will likely be restricted by low winter temperatures. Thus, P. reticulata in the Gillbach might not represent a threat for local fauna in Central Europe, but provide a unique semi-natural experiment for various questions related to local adaptation of invasive species, as well as ecological interactions with indigenous species."
I wonder if the German government considers this a part of the ecosystem now since they've been there since the 1970's, I have yet to find an article of them doing something about the invasive fish

What I found most interesting is that it seems that all the guppies reverted to almost 'wild' type endler-style guppies despite the fish that were introduced were reported to be monocolour/typical guppy patterned. Also the fact coldwater tolerance for these species is not that much different from your 'average ornamental' guppy (12-13 Celsius)

Article:
https://www.researchgate.net/public...es_Poecilia_reticulata_Peters_1859_in_Germany

Tl;dr: Invasive guppies/Convict cichlids/goldfish among other things have been surviving in a river in Germany, even breeding because of warm water from a coal power plant, and wont likely spread anywhere else due to harsh winters

Videos of the area:

Don't want to flood the forum with new threads so, I'll just post other interesting journals/documentation I find here. If anyone else finds anything cool feel free to send it here.
 

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Discussion Starter · #3 ·
Don't want to flood the forum with new threads so, I'll just post other interesting journals/documentation I find here. If anyone else finds anything cool feel free to send it here.
Heres a short one, not much too it but
tl;dr Freshwater Coralline algae found in Croatia, it's actually unable to survive in brackish water

Article:
https://www.researchgate.net/public...of_local_features_in_a_major_biome_transition
 

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There are more power plants in Germany with guppies in artificial heated water bodies. So, not just Gillbach. Btw, you can still catch those guppies overthere. Some friends of mine still do.
But overhere in Holland we had the same situation at the Royal blast furnaces in IJmuiden in the Netherlands. During the 1970's and 1980's guppies were kept the same way as in Gillbach. Nowadays, you won't them anymore in IJmuiden. And also these reverted to wildtype guppies.

Btw, if you'd combine several types of guppies in one tank, after a couple of generations of random crossbreeding, male offspring will revert to wildtypes as well.
 
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I found this an interesting post as well.

Caustionary tale though. You can't go dumping surplus fish in native steams more than one resident species can get displaced.

There are reports of farmed Atlantic Salmon escaping and potentially displacing Steelhead on Vancouver Is.

If you haven't seen it check out River Webs http://freshwatersillustrated.org/link/RiverWebs - features the maticulous work of a Japanese scientist investigating a small Japanese stream and how small introduced fish species shift the ecology.
 
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