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.
Noturus stanauli 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 protected
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.
The aquarium 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
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 6
x 6, 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 development.
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 adjacent eggs..
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 observation.
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 nauplii.
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 clutch.
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 T L,
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 is not
clear which one at this point). The remaining
adult still looks good and is probably the oldest
living pygmy madtom in the world!
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.
This article and photo's
are From the Conservation
Newsletter #2, 1 December, 2000 and are used on
ScotCat by permission.
is a non-profit
organization dedicated to the preservation of
aquatic biodiversity in the southeastern United
States. CFI's work with the captive propagation
of rare, threatened, and endangered species of
fish is designed to ensure their continued survival
in the wild.