t has recently come to my attention that some cold
water aquarists in the British Isles have an interest
in American species, especially catfish. I find this
most interesting, as I grew up in the Mississippi
watershed. That's a rather large area, something like
the size of Europe so I'll be a bit more specific. If
you have a detailed map of the United States you can
trace the Mississippi river down to just below its
confluence with the Ohio river. The next large river
down, about 50 miles, flowing in from the east is
the Obion. Tracing it back eastward and northward,
you will come to my hometown, Martin, lying between
the north and middle forks of the Obion river. I spent
my childhood and my early adult years roaming the
countryside there and along the Tennessee river, further
east by 70 miles.
In the drainage
area of the Obion river system, consistingof the North,
Middle, South and Rutherford forks in northwest Tennessee,
just 70 miles south of the Ohio river, the country
is largely given over to farming. Most farmers keep
some beef or dairy cattle and so, dig small ponds
to provide water for their stock.
These ponds are usually 3 or 4 feet deep and rarely
more than 50 feet in diameter. They stay muddied all
the time due to the cattle. Almost invariably, they
are populated by Ameiurus natalis and Lepomis
cyanellus, the yellow bullhead and green sunfish
respectively. Locally they are known as the "mudcat"
and "goggle eye". These two species have
proven themselves ideally suited to the harsh environment
that a cattle pond provides.
In the larger tributaries of the Mississippi that
I have explored, the Tennessee, the Obion, and the
Hatchie rivers, A. natalis is comparatively
rare, the dominant catfish being the channel catfish,
Ictalurus punctatus, however, A. natalis
dominates in smaller tributaries and ponds. I can't
say with any certainty why this is so, perhaps because
A. natalis is better able to withstand the
low water and oxygen depletion of the smaller bodies
of water in the summer months. I have many times seen
ponds stocked with I. punctatus suffer massive
die-offs in August, but never a pond with A.
natalis, even when the pond was so over-populated
that the fish were stunted to a mature size of 4 inches
long. I have even seen this catfish surviving from
season to season in very shallow ponds that dry to
little more than a puddle in summer.
Having mentioned the stocking
of ponds with channel catfish, I. punctatus,
I should explain, that in that area of America, A.
natalis, locally "mudcat", is considered
rather worthless. The mudcat is aptly named, as it's
flesh has a distinctly muddy flavor. This can also be
true of the channel catfish, but is not normally the
case. The mudcat has a very large head in comparison
to the channel catfish, so it dresses out much lighter
than the latter of the same weight. Many ponds are deliberately
stocked with channel catfish and a hybrid sunfish,
Lepomis cyanellus x Lepomis macrochirus.
These sunfish produce predominantly male offspring and
thus can not overpopulate a pond. If it is discovered
that mudcats have appeared in the pond, it is considered
ruined and drained, since these fish will quickly take
over. Such infestations can be from several sources;
the transfer of fish from pond to pond by herons, tornados
emptying farm ponds and scattering their contents, including
fish, over a wide area, and small boys who release their
catches into new ponds.
I was once such a small boy myself, and having caught
three mudcats about 4 inches long from an overcrowded
pond one spring, I released them into a new pond. This
pond leaked and later in the year when the pond had
dried to little more than a puddle, the three catfish
had grown to about one pound each and hundreds of little
catfish were present.
The largest specimen of A. natalis I ever saw
weighed approximately 4 pounds. This was exceptional,
the normal weight is 1 to 2 pounds. In contrast, I.
punctatus regularly goes 4 four pounds, and I have
seen specimens from the Tennessee river weighing in
excess of 50 pounds. While 50 pounds is a rare catch,
the channel catfish weighing in excess of 10 pounds
are not.
In its native habitat in the Obion river water shed,
A. natalis survives winters in which the ponds
may be frozen over for as long as a month and summers
in which their ponds may dry down to as little as one
foot of depth and the water temperatures exceed 90 degrees
F.
In farm ponds, A. natalis has a variety of prey,
including Amnicola limnosa, the pond snail, several
species of crayfish, the tadpoles of several species
of frogs and toads, and in some ponds mussels of a type
similar to the Margaritifera margaritifera common
to Europe. Mussel is recognized as the favorite food
of catfish and it is common to see the stomach and intestine
full of mussels about 1/4 inch in diameter. The catfish
swallow these whole and then pass the shells. A.
natalis is in turn the prey of herons, snapping
turtles, and when the water is low, the raccoon, redtail
hawk and even the turkey vulture.
In the spring of the year, tight masses of A. natalis
fry can sometimes be observed at the surface of
the water. At this point the fry are 1/2 to 1 inch long
and they hold tightly together in a circular mass, touching
one another as the mass moves slowly around the pond.
This is usually observed in March or April when the
weather has warmed into the 70's F and after spring
rains. I would imagine that breeding A. natalis
would be no problem in the British Isles for anyone
with a goldfish pond. (Probably in the south of the
country, Ed. see
restrictions ) Releasing the fish into the pond
in the autumn, so that they go through the dormant cold
period, should yield hundreds of fry the following spring.
They would pose little or no threat to goldfish, other
than smaller fancy varieties. I have seen the two coexist
and flourish. One thing I would point out is that
the term 'cold water aquarium' is a misnomer.
Four months of the year, most of the waters at home
are hotter than tropical, and the water is still warm
enough to swim in up until October. The daily high
temps there just dropped below 80 F last week ( Beginning
of October). The waters of the larger rivers will run
in the 70's for the rest of the month, maybe well into
November, depending on the rain.
It should be noted that concerns about the release of
this fish into the natural habits of the British Isles
are probably valid, especially for smaller waters. In
the area of the Obion river watershed, this fish has
proven itself capable of dominating other more desirable
catfish species when conditions turn harsh.
