If you quietly stand by  still or flowing waters between March and August you may see small fish dashing around.  These are likely to be sticklebacks  named after the row of spines on their  dorsal fin. These spines can be raised and locked in place making them a prickly mouthful for  predators such as herons, kingfishers and pike!

             There are two species of stickleback in Northern Ireland:  the three spined and the  9 spined. The   3 spined is the  most common. The 15 spined stickleback is  also found but these are strictly marine. There is a small Hebridean  form  unique to Scotland called the spineless stickleback.

             The stickleback is most commonly seen  in the ocean but some  like the 3 spined  may be found in both fresh and sea water.  The 9 spined is  found only  in fresh water such as  peaty lochs, chalk streams, canals, ponds  and lakes.  These freshwater sticklebacks  have evolved features different from those of marine species, they have no scales although some may  have bony armour plates. Marine species have very prominent spines.  The maximum size  of  the  3 spined is up to  8 cm. They are matured when they are roughly 3 cm. The large 15 spined stickleback can reach 25 cm!

           Sticklebacks eat a  varied diet of  plankton, tadpoles, snails , worms. insect larva ,water fleas and  even smaller sticklebacks.

           The behaviour of  these  fish has been widely studied.  In both species it is the male that is the aggressive sex and  it is the male who cares for the eggs and the young They  have unusual mating behaviour .

            The males in the  3 spined  species  develop a red colouration and  then construct a nest from weeds held together by  ‘spiggin’ which is a kidney secretion . Very few fish in the world build nests. The nest is in the centre of the male’s territory, and he defends  it rigorously from  other male sticklebacks.  He attracts females to this  nest  by performing  a special zig zag dance  where he approaches a female in an erratic side to side pattern.  Females which are full of eggs, signal they like  him  by adopting a head up posture, and she  lays  her eggs  inside the nest where  the male  then fertilizes them. He  may try to court other females perhaps having several clutches of 200-300 eggs.  Once she has laid her eggs,  she leaves  the male to look after them. He  actively fans the eggs with his fins driving fresh water through the nest and   guarding  them  against other sticklebacks and fish  who might eat them.  They hatch 7-14 days later depending  on the surrounding temperature . He  may continue to guard the fry after they hatch. After  a  week the fry will disperse, and his job is over.   

               Both males and females have strong mate preferences .Females like flashy males and will choose males with redder colouration under their throats . A hypothesis is there is an association between red colouration  and health  but there is also evidence that it actually may be a faulty signal of male quality!  Males prefer  larger and longer females with distended stomachs!

               The nine  spined stickleback is smaller  with the males having a jet-black throat patch .Their courtship dance involves head down bobbing jumps  whereby the female is led towards the nest usually built inside a sheltered weed bed.  The two species never interbreed as their courtship dances are so different.

               This parental care,  the  large number of eggs produced  and the  colonisation of  a wide range of aquatic habitats means that the stickleback is truly a successful animal.

                                                                         TO  DO

              These very interesting fish can be easily caught with a net.  They can live in a large fish tank  with water from their  habitat and fed with small invertebrates caught with a fine net . Simply swish the net around in muddy and weedy areas of the pond or stream and transfer this to the tank. It is amazing how many small creatures will be found in this.  Only put one male in with two, possibly three females . Provide plenty of weed for hiding and  for the  male to build a nest. Keep the tank in a well-lit but cool spot. If you are  lucky the fish may breed .Whatever the outcome,  PLEASE return the fish to the wild to where  they were found.

                                                                  BOOKS

               Steve the Stickleback     by Dave Marchetti

               All about voles and Sticklebacks and Things   by Althea   National Trust

               Three spined Stickleback and their young    by Colin Milkins

               Nature trail Book Of Ponds and Streams      Usborne

               Pond and River    by Steve Parker    

Children's article on Sticlebacks by Maureen Graham Hon Secretary