CHAPTER II 
FISH AND THEIR NESTS 
LL fish, with the exception of a few species 
that are viviparous, lay eggs from which 
the young emerge; and although the majority 
of the parents pay little attention to the ova 
when once they have been deposited, yet, 
on the other hand, others build nests for 
their accommodation, and stand guard over 
them. 
Amongst British fish there are several kinds 
that are in the habit of constructing nests, the 
most familiar being the sticklebacks, of which 
there are three species. Two of them dwell 
in fresh water, and one inhabits salt or 
brackish water; the three-spined and the 
ten-spined sticklebacks favouring the former 
habitat, and the fifteen-spined stickleback the 
latter. 
The nest of the three-spined stickleback is 
composed of grass, fragments of floating straw, 
and fibrous pieces of aquatic plants. These are 
formed into a muff-shaped structure measuring 
33 
c 
