Early October 2012
My colleague Ioannis Karaouzas (HCMR) and I did some wondering round Attika to find sites for water/ecological quality sampling during the beginning of the month. I had been informed by a local Athenian naturalist, Dimitris Zarris that a population of fish were evident near Agios Stephanos. Agios Stephanos is perhaps the northernmost suburb of Athens - so the story and his photos on fb came as a surprise.
Ioannis and I headed exactly to the spot. And lo-and-behold fish! Now, in our Med-type thermo-xeric tiny and degraded streams you do not often find fish! But in this case the tiny-tiny streamlet had four pools (along a 100 m stretch) and they were FULL of fish. Ioannis collected waterbugs and I collected the fish. I placed them in a formalin solution and collected some in ethanol (somewhat sloppily, but anyway- I will do better next time!).
The result is that we have a species of Chub - a species probably native of Greece - but perhaps not a native of this tiny stream. However, they are surviving, reproducing and large individuals over 20 cm. are common. The species is called "Potamokephalos" in Greek and belongs to the genus Squalius. We cannot yet identify the exact species - since several are found in this country and the systematics is difficult (if not totally confusing to amateurs). So the large fish in the photos below are of Potamokephaloi...
We also found the Marathon Minnow (Pelasgus marathonicus)- this is 6th site the species has been located in Attika (well two are right on the border with Beotia). The photo below with the small fish is the Marathon Minnow (Attikopsaro in Greek).
The map shows the site - it is a streamlet with perrenial water that enters Marathon reservoir - very interesting.