Borrow the Bugs, Leave the Frogs
Freshwater bugs are easy to catch, but challenging to keep. As for tadpoles, declining frog numbers mean they are now protected.
CAPTURE: USE A NET AND A BUCKET
Use a net and a white bucket to see what you have caught. You must return any tadpoles to the water-source where you found them. No stocking your pond!
CARE: TEMPORARY PETS
Why aren't water insects super popular pets? Because they are hard to keep... not alive, actually in the tank! Because unlike crabs, yabbies etc, most aquatic insects can fly away!
PHOTOGRAPHY: USE A MACRO LENS
A smartphone with an extra macro lens worth a few hundred DKK is sufficient to take excellent pictures of the creatures. A small, narrow fish tank will limit distortion via refraction.