Curious about mudminnows

Some people feel good when they are exercising, some others while they play music. For me, it has much to do with being curious about some animal or plant. Like this time, when I was curious about little fish called mudminnows.

A small net

It started with a small hand-held net years before. Armed with this net, I was discovering the underwater world of fish and creepy crawly animals which bite unless you hold them in a very specific way. I used to bring my catches home and observe them in an aquarium for a while. Like this, I got to know the local fish and invertebrates pretty well. Back then there was no internet, and people relied on books and magazines to share knowledge. There was a tiny book with pretty good photographs which was highly regarded as the best source of information on native fish. For each species, there was a picture and a short information on how to identify it. One of these fish stood out to me. It was called an »American mudminnow« (Umbra pygmaea) and it looked different from all other fish.

Dutch American Mudminnows

But it was a magazine article which triggered my curiosity. I read how this fish breathes air and can survive in water which has such a poor quality other fish die in some minutes. Perhaps more importantly, it told where to find them: Veldhoven. This is a place in the Netherlands, the country where I grew up and where I was then still living back then. In a specialised bookstore, I obtained a detailed map of the area; remember this was before Google maps, before the internet, and before GPS. I got on a train and rented a bicycle. For an entire day, I cycled around the place and checked all kind of ditches, streams, and pools. I paid particular attention to the dirtiest water because there only mudminnows could survive. I found several native fish, but no mudminnows. However, I still recall the smell of the mud in some of these places.

And Finally … 

By the end of the day, when it was almost dark, I was quite tired. I stopped one last time. Not at another dirty ditch, but at a beautiful fen with crystal clear water and many plants. My tiredness didn’t lessen my curiosity, and I couldn’t resist pulling my net through the water. And there it was: an American mudminnow. The fen proved to be full of them, so full that each haul with my small net brought a few of the little fish ashore. Since they are not legally protected, I took some home. In my aquarium, each of them defended a small territory. They ate earthworms and water fleas but didn’t like dry fish food. And most special: they were curious little fish! When I dropped a small stone in the water, they rushed towards it to inspect it. The one in whose territory the stone landed dared most and hovered above it, standing head down and tail up in the water to take a close look at the new stone.

Happy With an Unwelcome Fish

They were so interesting that I never quite understood why other people perceive them as drab but true, they are not colourful, and they can’t be kept together with other fish species. This has nothing to do with their requirements: they thrive in any water quality. But they can be rather aggressive and bite pieces out of fins of other fish. In later years, I encountered them a few times during field surveys for amphibians. Since these American mudminnows predate on amphibian larvae, they are in fact an unwelcome invasive species in the Netherlands. But I remember that day which ended at the fen and the incredible feeling of achievement when I finally had them in my hands.

Native European Midminnows!

Now try to imagine how I felt, many years later, when Jana and I went to see native mudminnows (Umbra krameri) in Slovenia. Again, after searching for a long day, we found them. This mudminnow is an endangered species and protected by law in Slovenia. While we obtained a permit for catching them in the framework of making an identification guide to freshwater fish, we did not take any with us and set them free immediately after taking some pictures.

On our Amphibian, Reptile and Fish Study Tour we will also search for small fish. We might not see mudminnows, because they occur in a different part of the country. Instead, we aim to see loaches, gudgeons and freshwater gobies!

A wonderful serenity has taken possession of my entire soul, like these sweet mornings of spring which.

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