These fish are young Ide and the picture on top shows a young Asp that has a more pointed head, a bigger mouth and pointed fins. I presume they are about four weeks old because on May 8. I caught an Ide that was producing eggs when pressure was applied to the abdomen.
It is pretty hard to be certain about the species on these small fish, so I caught a few of the thousands along the banks to let them grow a little bigger. Thus far it seems to be mostly Ide and some Asp (Aspius aspius).
The Asp is an exotic species native to the Danube area where it is getting rarer. In the larger Dutch rivers the Asp is one of the most abundant species now. More and more species from the Danube area are colonizing the Rhine river system and quite a few are becoming dominant species. Recently there are a lot of species from the gobio family.
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