wrote in
ups.com:

I was wondering if anyone knew exactly what type of fish these are? I
suspect that they may well grow too big for this tank, and will
probably not be suitable to keep for too long, but I would like to
check before I break the news to the children!!
http://www.kidsinaction.org.uk/fish.jpg

I think that they are minnows (Phoxinus phoxinus), and unlike most Eurasian
wild fish, they are actually suitable for normal home aquariums. Small
(max. 10 cm / 4"), rather hardy, and should learn to eat normal flakes.

If you are still going to release them please do that rather quicky. Winter
is arriving and waters are getting colder. If the fish are now indoors in
warm water, it will be quite a shock for them to get back in their chilly
home water. Releasing them next summer will be ok.

Liisa