young sticklebacks between 2 and 4 cm 
 the 3 spined stickleback is a small native fish common and widespread across the uk found in most aquatic enviroments ,from large lakes and rivers to small streams ,ponds and even puddles and ditches it is highly tolerant of pollution and can be found in waters too polluted for other fish it can also be found in brackish enviroments and even in salt water ,sticklebacks are carnivorous and will eat almost any small creatures they can fit in there mouth including small aquatic insects ,midge larvae ,zooplankton ,worms and will even eat hydra and can help control infestations of them ,they can also be fed frozen bloodworm and daphnia ,however due to there small size there is usually enough food in decent size pond to naturally sustain them ,3 spined sticklebacks live between 1 and 4 years depending on water conditions mainly temperature and availibility of food and can reach a max size of 8cm however a size of 3 to 4 cm is more common ,they are the second smallest native fish after the 9 spine stickleback which makes it highly suitable for small wildlife ponds ,they are also easy to breed so you can create a self sustaining population in your pond.