OUR HERITAGE OF THE FRESH WATERS 
93 
growths revealed on a cross-section of a 
tree trunk, which tell its age. 
Studies of the scales of Whitefishes in 
the Great Lakes have shown that the 
scale characters are so well defined that 
they indicate the age of the individual 
fish and the rate of growth of the species. 
Scales from Whitefishes hatched and 
reared in the New York Aquarium and 
therefore of known age have been used by 
Government biologists in checking the 
results of studies of the scales of wild 
fishes. 
The sexes of fishes are not as readily 
distinguishable as in the case of birds. 
Males and females are usually so much 
alike that only the expert recognizes the 
differences, and in many species the dis¬ 
secting knife must be employed to deter¬ 
mine the sex. 
The colors of fishes vary somewhat ac¬ 
cording to the waters which they inhabit, 
and this applies also to fishes held in cap¬ 
tivity, where their colors tend to become 
more subdued. The fishes of exhibition 
tanks, however, brighten their colors dur¬ 
ing the spawning seasons, much as do 
wild fishes. 
The habits of fishes have not been stud¬ 
ied as thoroughly as have those of birds, 
mammals, and other vertebrated animals. 
Books on fishes are largely of two classes: 
those written by anglers, relating chiefly 
to methods employed in the capture of the 
fish, and those written by the systematic 
naturalist, dealing chiefly with classifica¬ 
tion and distribution. 
A BIG FIELD FOR SCIENCE 
In neither class of books is the life of 
the fish in its own environment very fully 
considered. There are, of course, satis¬ 
factory life histories of certain common 
species, especially those inhabiting the 
smaller streams, and fish-culturists are 
contributing new information on the ways 
of fishes reared in ponds. 
Since the keeping of fishes in aquariums 
became common, many important facts 
have been recorded, but observations on 
creatures in captivity can manifestly deal 
with but little of their real life. 
For many important facts relating to 
the senses of fishes we are indebted to the 
modern biological laboratory. Facts based 
on scientific experiment relative to fishes’ 
powers of hearing and memory, their 
color changes, sleep, electrical and poison¬ 
ous properties, the sounds they make, and 
so on, are slowly being made apparent. 
The naturalist who can devote himself 
to the observation of the ways of fishes 
will find a fascinating field and contribute 
new facts to science. 
SPOTTED CATFISH (Ictalurus punctatus), 
COMMON BULLHEAD (Ameiurus nebu- 
losus) and other Catfishes 
{For illustration see Color Plate, page iii) 
There are many kinds of Catfishes in the United 
States, all of which belong naturally to that part 
of the country lying to the east of the Rocky 
Mountains, those now abundant in some States 
west of the Rockies having been introduced. 
Catfishes are of considerable importance com¬ 
mercially. The fishery statistics of a few years ago 
show that the annual catch for market exceeded 
14,000,000 pounds, but to-day the supply is much 
smaller. 
Since they are easy to catch, the total of those 
taken everywhere with hook and line can only be 
conjectured, but it may possibly equal the quantity 
yielded by the net fisheries. 
As Catfishes in general have the h^bit of guarding 
their nests and protecting the young, the supply 
holds out well in spite of exhaustive fishing. Such 
habits also as feeding chiefly at night and feeding 
but little in winter contribute to their preservation. 
The Blue Catfish, inhabiting the Mississippi 
Valley, is the largest and best of all as a food-fish. 
It occasionally attains a weight of 125 pounds and 
8o-pound specimens are not uncommon, but like 
other fishes taken in large numbers, the average 
weight is only a few pounds. 
The Blue Catfish is less inclined to live in muddy 
waters than some other species, preferring the 
clearer and swifter streams. It is a clean feeder, 
living much on fifehes and Crayfish. As a game 
fish it is one of the best in the Catfish family, 
taking many kinds of baits, and is a strong fighter 
on the line, but never adds to the angler’s thrill by 
leaping from the water. 
The Blue Catfish is decidedly given to migratory 
movements according to seasonal changes in tem¬ 
perature, gathering in the more southerly parts of 
its range in winter. 
The Spotted Catfish {Ictalurus punctatus) belongs 
in the Mississippi Valley and the Great Lakes. 
It does not reach the size of the Blue Cat, seldom 
weighing as much as 25 pounds. Like the Blue 
Catfish, it is a trim and active fish. There are 
four species in this genus, all having forked tails. 
One of the best-known Catfishes is the Common 
Bullhead {Ameiurus nebulosus) inhabiting streams, 
lakes, and ponds of the Eastern and Middle States 
and distributed as far westward as the Dakotas 
and Texas. Another fish of this round-tailed genus 
is the Black Bullhead {Ameiurus melas), having 
much the same distribution. The Bullheads are 
easily raised in ponds, and under proper manage¬ 
ment yield a good supply of white and palatable 
fish food. All of our native Catfishes have tough, 
scaleless skins and small eyes, and all have eight 
barbels or feelers on upper and under sides of the 
mouth, which are useful in searching for food in 
the muddy waters that many of them inhabit. 
Catfishes make their nests usually in sheltered 
