The behaviour of very small fish

[vole-woman]

I was at a lake in Shropshire today and there were a lot of these little fish - minnows? - round the fringes. What seemed weird to me was the way they kept turning on their sides at the surface. At first I thought these fish were dead, but they soon turned back the right way and swam with the others.

Why would they do this? It really drew attention to them as they were flashing in the sun. I thought, great for any passing heron etc.

[The Woodman]

These are bream fry and I'm not sure why they're doing this. It could be an adapted feeding technique for taking chironomid/midge pupae or similar prey from the subsurface film just as they hatch. The fish having to turn sideways in shallow water to get the best chance of eating them.

Your seeing some interesting fishy stuff VW!

[vole-woman]

Wow, bream fry! Thank you. I was actually after some photos of damselflies/dragonflies, and I thought the lake would be teeming with them. But it wasn't.

[~T~]

Yep minnows are not found in lakes as they prefer running water though they do sometimes enter lakes where it is being fed by a river.

[vole-woman]

I didn't know that. In fact my knowledge of fish is tiny, full stop.

[The Woodman]

Originally Posted by ~T~

Yep minnows are not found in lakes as they prefer running water though they do sometimes enter lakes where it is being fed by a river.

Apart from the lakes in the Lake District where they can be quite abundant!

[~T~]

Originally Posted by The Woodman

Apart from the lakes in the Lake District where they can be quite abundant!

As long as the lakes are shallow and have a decent current then I suppose they would inhabit the edges.

[Fauna]

I would often watch the thousands of Perch fry swim around in large shoals at a local res. You would see some flashing on stones, most likely trying to remove lice ect. Many would also come to the surface to do this flashing, you would think this sort of behaviour would make them more prone to predation.

Makes me wonder if some of these parasite has (in part) an effect here, changing the fish behaviour to be predated...me thinking out loud??

[vole-woman]

I never knew fish could get lice!

[The Woodman]

Fish lice or species of Argulus are very common in certain waters.
Info here..http://www.pond-life.me.uk/fishhealth/argulus.php

The other external parasite often seen is the fish leech, Piscicola geometra. http://www.pond-life.me.uk/fishhealt...lageometra.php

Salmon get them too, one destructive louse in Scandinavia Gyrodactilus salaris, may have its sights set on the UK element of the north Atlantic population. If it does, there will be drastic measures taken to rid it from rivers.

OK, nothing to do with the behaviour of very small fish.