or the past several years CFI
(Conservation Fishieries Inc.) has been working to
develop techniques to induce spawning in captive madtoms.
In the past, we have been very successful propagating
madtoms from wild collected eggs. While this has worked
well for a couple of species, where the situation
allows for the collection of wild nests, we could
foresee that there would be cases where this would
not be possible. Such a scenario would involve species
that are so rare that even if we were able to locate
nests, these should not be collected for fear of further
endangering the population. This is exactly the case
for the pygmy madtom.
is known from only two widely separated localities
in the Clinch and Duck rivers of the Tennessee Drainage.
A search of the literature and museum records revealed
that only about 25 museum specimens existed, and probably
fewer than 50 individuals have ever been collected!
This is in spite of extensive surveys by many fish
folks collecting at both known localities and other
nearby sites. Obviously, this is easily one of the
rarest fishes in North America!
The pygmy madtom is the smallest member of the genus
Noturus. Adults are less than 50mm total length
(TL). They are dark brown dorsally and nearly white
ventrally. This contrast of dark and light is quite
striking. Almost nothing is known of the biology of
this rare madtom. Most specimens have been collected
over shallow, fine gravel shoals with moderate to
swift flow, usually near the stream bank. For years
we have wondered about the possibility of propagating
pygmy madtoms. It was clear that the species was too
rare to think we would find nests to collect and rear.
We have had limited success spawning other madtoms
in our hatchery, mostly as a result of injecting hormones.
Clearly, madtoms could be spawned in aquaria, but
because of the rarity of this fish, and our reluctance
to handle them, we would hope to find a natural trigger
to induce spawning in these miniature catfish.
Our chance came this past
spring. On March 25, 2000, Dr. Rick Mayden and crew
were in our area collecting fish to photograph for
his upcoming book on the freshwater fishes of Alabama.
The day before we had been out helping them collect
snail darters, Percina tanasi in the Holston River.
The following day, they made a collection in the
upper Clinch River. Later that day we got a call
from Rick. They had managed to collect two pygmy
madtoms! They were aware of our efforts to propagate
madtoms and told us that they would turn the specimens
over to CFI. CFI is covered under the necessary
federal and state permits to handle these federally
We quarantined the two specimens
in a 55 gallon aquarium. One of the two madtoms
was considerably smaller than the other (the smaller
was approximately 30 mm and the larger was around
35 mm TL). Since pygmy madtoms are thought to have
a short, one-year lifespan, we were hopeful that
the size difference was a gender difference, rather
than an age difference.
was filtered with a large, air driven, sponge filter.
A natural gravel and sand substrate was provided
along with flat rocks and other cover items. The
fish were fed heavily with live blackworms, Daphnia,
mosquito larvae and frozen bloodworms (chironomid
larvae). Both individuals adapted well and slowly
increased in size.
By early July, the larger specimen was becoming
obviously gravid. The smaller one showed no signs
of filling out. Also, for the first time since they
were placed into the aquarium, they began to spend
time under the same cover objects. At this point,
we provided more cover, including empty mussel shells
and a 6x6î, unglazed ceramic floor tile. More
current was added to the tank, using a small submersible
water pump. Within a couple of days, the pair (at
least we hoped they were a pair!) took up residence
under the floor tile. Based on our other aquarium
experiences, we had discovered that freshly laid
madtom eggs are very difficult to handle and are
much more likely to develop problems than ones that
are several days old. Because of this, we chose
to leave the fish undisturbed for about a week in
hopes that if they did spawn, the eggs would stand
a better chance of survival.
On July 11th, we checked under the floor tile and
found the male guarding a small clutch of eggs!
The female was under an adjacent rock. The eggs
were removed from the custody of the male and transferred
to a plastic incubation tray filled with water from
the parentsí tank. There were 10 live eggs
and three empty chorions. The eggs measured approximately
3.8 mm in total diameter. Despite the small size
of the pygmy madtom, the eggs are nearly as large
as other madtoms we've had experience with. The
eggs appeared to have been laid at least a couple
of days earlier, and some showed distinct embryonic
and measuring the eggs, they were placed onto a
hatching platform, dubbed by Pat, a ìmadtom
egg wagonî. The ìwagonî was constructed
using plastic mesh (3x4mm) and PVC tubing. The platform
was constructed to provide water movement all around
the eggs, even from below. Water movement was facilitated
using a small air stone placed near the eggs.
Over the next few days several of the eggs turned
opaque and died. Leaving dead eggs in the clutch
invites fungal infection of the good eggs, so these
were carefully removed by pipette, or by inserting
the needle from a syringe into the egg and removing
the contents. We were very careful not to damage
The first egg hatched on July 18th and by the next
day, the rest had hatched. At this point, we were
down to four larvae. It was not clear if development
was progressing normally in the eggs that died,
or if they were even fertile. Our reluctance to
disturb the developing eggs prevented us from close
Over the next couple of days, the baby madtoms looked
great. Because the larvae have large yolk sacs (as
all madtoms do), feeding was not necessary until
the larvae began actively swimming.
By July 24th, one of the four larvae had died. This
was right at the stage where the larvae were beginning
their transition from reliance on their yolk to
feeding on their own. The remaining three looked
fine and were now accepting newly hatched Artemia
On July 29th, a second nest was discovered, being
guarded by the male pygmy madtom. We had noticed
the female still appeared to be somewhat gravid
after the first spawn and were hopeful that a second
spawn was possible. This nest was somewhat larger
than the first, consisting of19 eggs. At the time
we discovered the nest, these eggs were probably
at about the same stage of development as the first
The second clutch
of eggs were treated much the same as the first
clutch. Again, there were some egg losses over the
next couple of days, but this time we managed to
bring 10 eggs to hatching! The first eggs
hatched on August 8th, 10 days after collection.
The spawning adults and incubated eggs were held
at approximately 73 degrees F. At this point, the
babies from the first spawn measured 18 mm TL!
As the young madtoms
grew, they were put together in a single 20 gallon
aquarium which is part of a much larger aquarium
system, and that is where we currently keep them.
The young madtoms have adapted well to chopped,
live blackworms. While the madtoms are rarely seen
out from under cover, they do tend to be most active
shortly after the lights go out in the early evening.
For this reason, we believe that pygmy madtoms may
At the time of this writing, all 13 madtoms
are doing great. They now measure 35 mm TL, which
is as large, or larger than the adults we received
from the Clinch River in March. In October, one
of the parents died (it ís not clear which one at
this point). The remaining adult still looks good
and is probably the oldest living pygmy madtom in
Our experience here opens up the possibility
for reintroduction work with this and other rare
madtoms. Already, we are able to look at several
big-river sites and hope that some day they might
serve as potential homes to this rare fish that
almost certainly inhabited much of the upper Tennessee
River in the past.