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Species Name:    Hoplosternum littorale
Common Name:                  (Brown Hoplo)

 

I.  TAXONOMY

Kingdom Phylum/Division: Class: Order: Family: Genus:
Animalia Chordata Osteichthyes (Actinopterygii) Siluriformes Callichthyidae Hoplosternum



The non-native brown hoplo, Hoplosternum littorale. Photo courtesy USGS, Photograpger Howard Jelks.

  

Crested caracara, Caracara cheriway, with a juvenile brown hoplo in its beak. Photo courtesy Arnold Durbin.

Species Name: 
Hoplosternum littorale Hancock, 1828

Common Name(s):
Brown hoplo, Armored Catfish, Curito, Cascadu, Atipa, Tamuata, Hassa

Species Description:
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 possesses teeth (GSMFC).


II.  HABITAT AND DISTRIBUTION 

Regional Occurrence:
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).

IRL Distribution:
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 of Titusville.


III. 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 4 years.

Abundance:
Unknown.

Reproduction:
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).

Embryology:
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).


IV.  PHYSICAL TOLERANCES

Temperature:
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 al. 1996).

Salinity:
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.

Dissolved oxygen:
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).


V.  COMMUNITY ECOLOGY

Trophic Mode:
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).

Associated Species:
None reported.


VI. INVASION INFORMATION

Invasion History:
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 (ISSG).

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 reagional establishment (ISSG).


VII.  REFERENCES

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 Biology 36:133-140.

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 Resources 11:173-185.

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. Available online.

Machado-Allison A. 1986. Aspectos sobre la historia natural del curito Hoplosternum littorale (Hancock, 1828) (Siluriformes, Callichthyidae) en el bajo llano de Venezuela: desarollo, alimentacion y distribucion espacial. Acta Cientifica Venezolana 37:72-78.

Mol J.H. 1994. Effects of salinity on distribution, growth and survival of 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.

Nico L.G., Walsh S.J., and R.H. Robins. 1996. An introduced population of the 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 Naturalist 3:451-466.

Nico L.G., and P. Fuller. 2007. Hoplosternum littorale. USGS Nonindigenous Aquatic Species Database, Gainesville, FL. Available online.

Pascal M., Hostache G., Tessier C., and P. Vallat. 1994. Cycle de reproduction et fecondite de l'atipa, Hoplosternum littorale (Siluriforme) en Guyane Francaise. Aquatic Living Resources 7:25-37.

Ramnarine I.W. 1994a. A field trial of the semi-intensive culture of the cascadu, Hoplosternum littorale (Hancock, 1828). Tropical Agriculture (Trinidad) 71:135-138.

Ramnarine I.W. 1994b. Larval culture, development and growth of the cascadu, Hoplosternum littorale (Hancock 1828; Callichthyidae). Aquaculture 126:291-298.

Reis R.E. 1997. Revision of the neotropical catfish genus Hoplosternum (Ostariophysi: Siluriformes: Callichthyidae), with the description of two new genera and three new species. Ichthyological Exploration of Freshwaters 7:299-326.

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 of Fishes 20:219-227.

Report by:  J. Masterson, Smithsonian Marine Station
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Page last updated: September 30, 2007