An article on the nomenclature, distribution and husbandry of the cichlid genus Mesonauta.
As far back as I can remember, despite my avowed fondness for the members of the genus Crenicichla,
I have always kept either Keyhole cichlids or Festivums. Keyholes and Festivums will
always remain near the top of my favorite-list. Perhaps their innocuous and pleasant
aquarium behavior reminds me that cichlids do not necessarily have to be terrors in
aquaria. They are neither flashy nor easy to breed but they are not difficult to keep and
get along famously with most fish and plants you could throw in with them. For all my
years of keeping these two fishes, I managed to spawn Keyholes only once and still have
not had any luck with Festivums. You see Festivums everywhere so perhaps due to their
commonness I was not motivated to give them the conditions they deserve to spawn.
Festivums have been in the hobby for a long time and you see them illustrated in Innes'
old books and articles. They became popular aquarium fish in the 50's and 60's before the
invasion of the Rift Lake cichlids, and were then known as Flag cichlid, ("Acara
bandeira" or Flag Acara in Brazil) a name they still occasionally go by. Most
shops have become hip and prefer to call them just Festivum. In the early days of the
hobby, a major source of export was Guyana (British) and we were used to buying "Cichlasoma
festivum". Then, when Manaus, Brazil and Iquitos, Peru became larger points of
export, we started seeing new "color morphs" of this widely distributed species.
"Cichlasoma festivum" was believed to have a very large distribution
all the way from Guyanas in the north to Peru in the West, Rio Tocantins in the East and
Rio Parana in the South.
As it turns out, in 1991, Kullander and Silfvergrip published a paper explaining that
our "Festivum" actually was a number of similar, biologically distinct species
deserving once again a genus of their own Mesonauta, possibly in reference to
their preference for middle strata of the water column and/or to the position of the
dorsal fin origin posterior to the pelvic fin origin which was Gunther's primary
OK... so what is the fish you have in your tank that you thought was a regular
Well, the answer depends on where it is from. Mesonauta insignis (the type
species of the genus) is found in the Rio Negro and Rio Orinoco. This is what gets
exported out of Manaus and Barcelos, Brazil. Distinguishing character: of the 7 faint
vertical bars that these fish exhibit when stressed, 2 and 4 are joined and the scales
above the diagonal "flag" bar are reticulated.
M. egregius is found in Rio Meta, Colombia. It is occasionally seen on price
lists of fish from Colombia as Festivum. Distinguishing character: bar 3 divided into two.
It is quite certainly M mirificus if it was collected anywhere near Iquitos,
or Pebas, Peru. Distinguishing character: divided bar 3 and there are think horizontal
lines above the diagonal flag bar.
Southern Peru (Rio Madre de Dios), Bolivia and in Paraguay has the true M. festivus.
Unfortunately, this is not a hotbed of aquarium fish export and so, it is unlikely that
most of us ever had the real "Festivum" - kinda like the story with Geophagus
surinamensis. Distinguishing character: bars 5 and 6 are joined.
Rio Xingu and Tocantins have M. acora. Despite increased collection in these
two rivers, attention is mainly focused on colorful Loricariids and Pike cichlids. Thus, M.
acora is unlikely to be found in your tank. Distinguishing character: divided bar 4
The latest (and most likely not the last) addition to the genus is the fish that was
exported into the hobby so often in the 50's and 60's from Guyana, Mesonauta
guyanae (Schindler, 1998) described from the Essequibo River in Guyana. There is
limited export from Georgetown and so, you are certainly likely to have M. guyanae.
I have yet to read any commentary on the authenticity of the status of this new species
from other ichthyologists (read: Kullander)
How nice and complicated! Some don't care what species they have and others do. When
comfortable, the said bars are not very visible on these fish. You can always put them in
a plastic bag and shake them up a bit and wait for the fright patterns to emerge -
you can tell pretty easily then. Cruel? Uh-huh. Effective? Certainly. You decide.
So, there are six described species, and Kullander and Silfvergrip believe there are a
couple of other undescribed forms out there.
Now that the whatiszit questions are out of the way, how do you raise and breed these
species? Heck, don't ask me. I've never bred them. Here's a secret - I've never bred
Angels either, of course, I'm talking about wild ones. I can make pike cichlids do the
Mambo but no-can-do with Festivums and Angels.
Feeding Mesonauta is very easy - they eat anything that falls in the tank but
prefer to eat near or off the surface. All live foods are appreciated and juveniles LOVE
Members of Mesonauta are found just about everywhere in the Amazon and they
are very commonly encountered. They are found near the surface or just below it, always in
still waters. Unlike most other cichlid species, Mesonauta, when threatened, do
not dive down for cover but swim away while staying near the surface. A characteristic of
surface levels of most still bodies of waters in the Amazon is high temperature. I have
seen M. insignis in riverside lakes and pools in stagnant water at 90°F and pH
5.4. I had no oxygen meter but would guess that dissolved oxygen was low. The only other
cichlid species found with them in that location (Rio Uatuma, Brazil) was juvenile Satanoperca
and Acaronia nassa. Fluviphylax pygmaeus, a tiny livebearing fish that
mimics surface air bubbles with their eyes were the only non-cichlid fish found in the
A few SACSG members (Lee, Wayne, Jim Herman, John Niemans, Nathan Okawa, Wanda
Jacobson, Stan Sung and yours truly) went to Peru in 1998. We caught M. mirificus
in Rio Momon, near Rio Nanay and in Cocha Vieja, an oxbow lake near the confluence of the
two rivers. The water here was very soft (10uS conductivity) and the pH was 7.0. The
temperature was a mild 80°F. Here they were found with Apistogramma bitaeniata,
Crenicichla lucius, Satanoperca jurupari, Heros appendiculatus, Cichla sp,
Aequidens tetramerus, Hypselecara temporalis, and Angels.
Nathan, Wayne and Jim also went to Puerto Ayacucho, Venezuela on the Orinoco couple of
years ago and observed M. insignis and many other species while snorkeling.
Nathan described their behavior in the wild thusly - they actually school! They hang out
in small groups of 6 to 8 adults and when one moves, the rest follow. My observations of
the same species in shallow blackwater areas in Brazil are that they form loose
congregations with comfortable elbowroom of about a foot between individuals. This
behavior is not unlike that displayed by Pterophyllum species. Given this
congeniality in the wild, it is unusual to encounter a rogue "Festivum" in
aquaria but I recently spoke to Al Knowles and he described just such a scenario. Still,
when Mesonauta fight, most aggression is limited to ritual displays of rushing
and nudging. Rarely do unpaired harass a conspecific to death or even shred each other's
Most females attain 4-5 inches when full grown but large males sometimes grow to 6
inches. I must mention that I have never seen a 6-inch specimen in the wild.