I also have had this idea in my head for several months. This will by FAR be the most difficult tank I've ever set up because of how hard the fish will be to obtain. But, I think it would be awesome to have an Ireland native stream tank, or at least a Western Europe native one. I'm about 50-60% Irish and about 90% Western-Central European (Irish, French, German, Italian) so it'd be amazing to have fish from country(ies) of my origin. Like I said though, the fish would be VERY hard to obtain, especially for me living in the US. But if anyone can get there hands on any of these fish and/or any other ones native to Ireland, UK, Western Europe, etc and can ship them to Southwestern Pennsylvania, please either post here or PM me because if I can get some of these fish this will be my first choice for one of these tanks and I'd be very happy to buy some for those who are willing to ship them. Or of anyone knows a source that is either in the US or can ship to the US that sells European natives.
-Phoxinus phoxinus (Common Minnow)
-Gasterosteus aculeatus (Three-Spine Stickleback) (Circumpolar species native to both North America and Europe, unfortunately the part of the US where it can be found would involve a several hour trip for me)
-Gobio gobio (Gudgeon)
-Cottus gobio (European Bullhead/Sculpin)
-Any other small stream fish native to the places listed above.
(Following species would be growouts and would be upgraded later but I'd still be possibly interested in some)
-Cyprinus carpio "Mirror" (Mirror Carp)
-Cyprinus carpio "Leather" (Leather Carp)
-Thymallus thymallus (European Greyling)
-Abramis brama (Bream)
-Barbus barbus (Barbel)
-Leuciscus cephalus (European Chub)
-Leuciscus leuciscus (Common Dace)
-Perca fluviatilis (Redfin Perch)
-Rutilis rutilis (Common Roach)
-Tinca tinca (Tench)
-Any other medium-large sized fish native to the above listed areas.
Species that I can obtain myself include the normal strain of Common Carp (Cyprinus carpio), the Brown Trout (Salmo trutta) , and the Northern Pike (Esox lucius). I should also mention that in PA, it's illegal to own Ruffe (Gymnocephalus cernuus) or Rudd (Scardinius erythropthalmus) and we all know that 95% of us don't have a big enough tank for a Wels Catfish

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You guys can see how much thought I've put to a setup like this prior to this thread

. Can't believe I forgot to mention it until now.