is common enough in the pools at low tide, but not easy to find. You can
look at him, yet not see him! For he takes the same colour as the rocks
and sands of his home. Amid the glinting lights and shadows of his
rock-pool, with a background of sand, rock, and weed, this little fish
is nearly invisible. Of course it is a dodge, and a useful one, to
escape the eye of the enemy!

Perhaps you will not think the Spotted Goby so clever at nest-building
as the Stickleback. He likes to use a "ready-made" house, whereas the
Stickleback finds his own "bricks and mortar." In the pools of the shore
there is no lack of houses to let, the empty homes of shell-fish are
there in plenty. So the little Goby, when nesting time comes, hunts
round for the empty shell of a Cockle lying with its hollow side to the
sand.

This shell is to be used as the roof for the nursery. The Goby's next
task is to make a hole beneath the shell. He sets to work and, by
scooping out the sand, makes a hole about as large as a marble. To keep
the sand from tumbling in, he smears the hole with slime, which soon
binds hard like mortar. Now the nursery is nearly ready; but a
passage-way is made, passing under the edge of the shell, and then, to
make things quite safe, the whole roof is covered with sand: it then
looks more like a bump in the sand than a fish-nursery.

The female Goby enters the nest, and leaves her eggs in it; and then the
little father fish is left in charge. He rests on the sand, near the
entrance. When the little ones appear, he seems to think he has done his
duty. So away, he swims, not staying, like the father Stickleback, to
guard the youngsters. Again we see that the father, and not the mother,
is the builder and nurse.