The brown hoplo, Hoplosternum littorale is nearly unmistakable with its
plate-like armor consisting of two rows of large bony scales running along the
length of each side of the body. The armored appearance of this animal gives
it the alternate common name armored catfish. Individuals range in color from
dark brown to black. Two pairs of long chin barbels are present. (FWC).
This species exhibits sexual size dimorphism with males growing larger than females
(Machado-Allison 1986, Nico et al. 1996). In breeding males the enlarged
pectoral spines are bright red in color and curve upward at the tips.
Potentially Misidentified Species
The armored appearance of the brown hoplo makes positive identification on the
east coast of Florida relatively easy. On the Gulf coast, Hoplosternum littorale may be
confused for the cascarudo (Callichthys callichthys). Another non-native armored
catfish of family Callichthyidae, cascarudo that has been collected from Gulf coast drainage ditches
but is not considered to be established there. Brown hoplo has teeth on
both the upper and lower jaws, whereas only the lower jaw of C. callichthys
HABITAT AND DISTRIBUTION
The native range of the brown hoplo is in tropical eastern South America. Reis
(1997) indicates the species is widespread in the river systems east of the
Andes and north of Buenos Aires.
The non-native Florida range of the brown hoplo currently encompasses much of
peninsular Florida within which populations are established in several drainage
basins from the St. Johns and and Kissimmee River drainages to Lake Trafford
(Nico et al. 1996, Nico and Muench 2004). The range of the species is
currently expanding northward in the state (Nico and Fuller 2007).
Nico et al. (1996) reported the first occurrence of Hoplosternum littorale in the IRL
region. This occurrence consisted of a population of hoplo living in
stormwater ditches adjacent to the IRL in Brevard County. The species has
been collected and positively identifieed in Brevard and Indian River counties. Nico et al. (1996)
suggest that it is likely to occur in other counties of the IRL watershed and may be
established there as well. Hulen (2004) suggests that official collection
records maintained by FWS, USGS, FLMNH, etc., are incomplete and that H.
littorale probably exists in most of the habitable freshwater systems south
LIFE HISTORY AND POPULATION BIOLOGY
Age, Size, Lifespan
Hulen (2004) reported adult brown hoplo in his study as having a standard
length (SL, measured from stout to caudal peduncle or base of the tail) ranging
from 136-197 mm. Hostache and Mol (1998) indicate a lifespan of approximately
Brown hoplo exhibit high fecundity. For
individuals in their native habitat Hostache and Mol (1998) report
an approximate lifetime fecundity of greater than 300,000
eggs/female. Hulen (2004) suggests a lifetime fecundity of at
least 50,000 eggs/female in Florida.
Sexual maturity is reached at approximately 80-86 mm SL
(Machado-Allison, 1986; Nico et al. 1996).
In native waters the reproductive season coincides with the rainy
season spanning from November through May (Winemiller 1987, Pascal
et al. 1994, Ramnarine 1994a, Mol 1995). In the Indian River
Lagoon region of Florida the breeding season occurs during the
summer months, as examination of multiple adult specimens by Nico
et al. (1996) in collected in December revealed that none
possessed developed gonads.
Males construct bubble nests in vegetated shallows that they cover
with aquatic plants and leaf litter (Mol 1994). Observations of
pond-reared hoplo suggest some nests remain unused while others are used
multiple times by several different spawning females. Females can
spawn more than a dozen times over the course of a spawning season
and each spawning event results in an egg mass containing from
5,000 to more than 50,000 eggs (Machado-Alliso 1986).
Breeding males are aggressive in protecting their territory, using
the enlarged, hook-tipped pectoral spines as defensive weapons
(Nico et al. 1996).
Embryonic development inside the eggs is rapid relative to the developmental
rates of related species. Under culture eggs hatched just four days after
spawning. Rapid larval growth continues after hatching, such that young reach
40 mm SL in under two months (Ramnarine 1994b, 1996).
Low temperature may ultimately prove to be the key factor limiting the northern
range limits of Hoplosternum littorale in Florida. Temperature is likely to be less
important in mediating brown hoplo populations in central Florida where mean
temperatures are milder than in parts of the species' native range (Nico et
Preferred habitats within the native range of the hoplo vary from freshwater
to brackish marshes up to 16 ppt salinity (Nico et al. 1996). Mol (1994)
reported slower rates of growth at reduced salinity and high larval mortality
in rainwater. This author also noted that the native freshwater systems in
which this species is abundant tend to be rich in dissolved minerals.
Brown hoplo is a facultative air breather and is tolerant of
hypoxic conditions as well as acidic waters and elevated hydrogen
sulfide levels (Hulen 2004).
Brown hoplo is an opportunistic omnivore/scavenging generalist that consumes a
variety of benthic invertebrates, algae and detrital material. Individuals
exhibit an ontogenetic shift from a microphagus larval and juvenile diet of
rotifers, copepods, cladocerans, etc., to an adult diet consisting of larger
crustaceans, insects and insect larvae, detritus and algae (FWC, Winemiller 1987, Mol 1995). Feeding activity occurs
primarily during the night (Boujard et al. 1990).
The first reported of that H. littorale in Florida was in 1995 when a
specimen was collected from a drainage ditch within the Indian River Lagoon
watershed in Brevard County. Nico et al. (1996) reported the subsequent
collection of more than 30 individuals from the area. Although none of the
fish were sexually mature the author suggested at least one breeding event had
occurred based on the numbers collected. No source of this initial Florida
introduction was confirmed (Nico et al., 1996).
The spread of H. littorale through the Florida peninsula in the decade
following the initial collection has been rapid. Hulen (2004) suggests the
species may now occur in a majority of freshwater systems south of Titusville
although state collection records do not yet reflect this assessment.
Potential to Compete With Natives
The brown hoplo's broad tolerance in regard to salinity, dissolved oxygen
levels, and habitat disturbance allow the species to thrive in a variety of
habitats and potentially engage in competitive interactions with a number of
co-occurring species. The Gulf States marine Fisheries Commission suggests
that the adaptability and eurytopic nature of H. littorale may allow it
to become a dominant species in those aras where it becomes established.
Breeding males are aggressive and may direct their aggression toward co-occurring species.
Possible Economic Consequences of Invasion
Although there is no commercial harvest or culture of brown hoplo in Florida,
it is a food fish in its native range (FWC).
It remains uncertain whether H. littorale will become more broadly
established in the eastern United States or what impacts would result from
Boujard T., Keith P., and P. Luquet. 1990. Diel cycle in Hoplosternum
littorale (teleostei): evidence for synchronization of locomoter, air
breathing activity by circadian alternation of light and dark. Journal of Fish
Hostache G., and J.H. Mol. 1998. Reproductive biology of the neotropical
amoured catfish Hoplosternum littorale (Siluriformes - Callichthyidae):
A synthesis stressing the role of the floating bubble nest. Aquatic Living
Hulen K.G. 2004. Feeding and reproductive biology of the brown hoplo
Hoplosternum littorale (Siluriformes: Callichthyidae) in the St. Johns
River canal system, Florida: Implications for management. University of
Florida Dept. of Zoology invited symposium presentation.
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Hoplosternum littorale (Hancock, 1828) (Siluriformes, Callichthyidae) en
el bajo llano de Venezuela: desarollo, alimentacion y distribucion espacial.
Acta Cientifica Venezolana 37:72-78.
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three neotropical armoured catfishes (Siluriformes, Callichthyidae). Journal of
Fish Biology 45:763-776.
Mol J.H. 1995. Ontogenic diet shifts and diet overlap among three closely
related neotropical armored catfishes. Journal of Fish Biology 47:788-807.
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South American callichthyid catfish Hoplosternum littorale in the Indian
River Lagoon system, Florida. Florida Scientist 59:189-200.
Nico L.G., and A.M. Muench. 2004. Nests and nest habitats of the invasive
catfish Hoplosternum littorale in Lake Tohopekaliga, Florida: A novel
association with non-native Hydrilla verticillata. Southeastern
Nico L.G., and P. Fuller. 2007. Hoplosternum littorale. USGS
Nonindigenous Aquatic Species Database, Gainesville, FL. Available online.
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et fecondite de l'atipa, Hoplosternum littorale (Siluriforme) en Guyane
Francaise. Aquatic Living Resources 7:25-37.
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cascadu, Hoplosternum littorale (Hancock, 1828). Tropical Agriculture
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Hoplosternum littorale (Hancock 1828; Callichthyidae). Aquaculture
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(Ostariophysi: Siluriformes: Callichthyidae), with the description of two new
genera and three new species. Ichthyological Exploration of Freshwaters
Winemiller K.O. 1987. Feeding and reproductive biology of the curito,
Hoplosternum littorale, in the Venezuelan llanos with comments on the
possible functions of the enlarged male pectoral spines. Environmental Biology
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