(_Perca fluviatilis._)
This is a fresh-water fish and is generally distributed over Europe,
northern Asia, and North America, and so well known as to have been,
it is said, selected for the type of an entire family of spiny-rayed
fishes, the _percidas_, which is represented in European fresh waters
by several other fishes such as the pope and the pike-perch. It
inhabits rivers as well as lakes, and thrives best in waters of a
depth of not less than three feet; in large, deep lakes it frequently
descends to depths of fifty fathoms and more. It occurs in Scandinavia
as far north as the 69th parallel, but does not extend to Iceland
or any of the islands north of Europe. In the Alps it ascends to an
altitude of four thousand feet.
The shape of the body of the perch is well proportioned, but many
variations occur, some specimens being very high-backed, others low and
long-bodied. Sometimes such variations are local, and Agassiz and other
naturalists at one time thought it possible to distinguish two species
of the common perch of Europe; but it can be separated specifically
from the North American form. The brilliant colors of the perch render
it easily recognizable even at a distance. A rich greenish-brown, with
golden reflections, covers the back and sides, which are crossed with
five or seven bands. A large black spot covers the membrane between
the last spines of the dorsal fin, and the lower parts are bright
vermillion. In the large, peaty lakes of North Germany a beautiful
variety is not uncommon, in which the golden tinge prevails, as in a
gold-fish.
The perch is carnivorous and voracious. It wanders about in small
shoals within a certain district, playing havoc among small fishes,
and is therefore objectionable in waters where more valuable fry is
cultivated. Perch of three pounds in weight are often caught; one of
five would now be regarded as an extraordinary specimen, though in rare
instances we read of individuals exceeding even that weight. An old
fisherman, Mr. George Northrup, a man of rare intelligence, tells us
that of thousands of perch caught by him he never took one that weighed
above three pounds.
Perch are good, wholesome food and highly esteemed in inland countries
where marine fish can be obtained only with difficulty. The nearly
allied pike-perch is one of the best European food fishes. It is very
prolific, begins to spawn when three years old, in April or May,
depositing the ova on water plants.