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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.



Mesonauta festivus
(festivum)
Fishes
Exotic
Collection Info
Point Map
Species Profile
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Mesonauta festivus (Heckel, 1840)
Common name: festivum
Taxonomy: available through www.itis.govITIS logo

Identification: Mesonauta festivus has a deep body and short snout; the body is strongly laterally compressed with dark caudal and anal fins (Kullander and Silfvergrip 1991). Mesonauta species have an oblique lateral band extending from the mouth to the dorsal fin, and often have irregular vertical bars below the band and a prominent spot on the caudal fin base (Kaur 2022).
Size: reported to 12.1cm total length (Cella-Riberio et al. 2015)
Native Range: This species is widespread throughout South America: Paraná River basin, in the Paraguay River drainage in Brazil and Paraguay; Amazon River basin, in the Guaporé (Brazil and Bolivia), Madre de Dios (Peru), Mamoré (Bolivia), Jamari and Tapajós (Brazil) River drainages (Kullander 2003).
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences: A specimen was collected near a fish farm in the Tampa area (Hill and Tuckett 2018).
Ecology: Mesonauta festivus is a tropical freshwater species found primarily in lakes or along shores of the main channels of large rivers, but also in small oligotrophic streams with highly variable water conditions; it is commonly found in macrophyte stands (Pires et al. 2015). This species has a generalist diet that varies depending on water levels, consisting of detritus, periphyton, and aquatic macrophytes (Röpke et al. 2014). Reproduction is possible throughout the year, but peaks from May to June with a relatively small body size at reproductive maturity of 4.2 cm (Pires et al. 2015). Both parents tend the offspring keeping the fry between them while shepherding them to food resources (Pires et al. 2015). Juveniles have been observed in a posture that mimics a leaf, presumably for camouflage (Pires et al. 2015). Mesonauta festivus can moderate its metabolic rate and anaerobic metabolism to accommodate hypoxic environmental conditions (Heinrichs-Caldas and Almeida-Val 2021). It also has a high tolerance to high variation in other environmental conditions such as temperature, pH, and conductivity (Röpke et al. 2016).

Mesonauta festivus has been observed exhibiting some interesting behaviors. When feeding in groups the fish form a defensive ring to avoid predation by piranhas (Sazima and Machado 1990). Adults have been observed engaging in cleaning behaviors of other species, a behavior noted in marine environments, but extremely rare in freshwater habitats (Severo-Neto and Froehlich 2015).
Means of Introduction: aquaculture escape
Status: unknown
Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.
Remarks: Identification of the specimen caught by the Tampa Fish farm cannot be verified, as no voucher was retained. Another species, Mesonauta insignis, is reportedly more common in the trade and similar in appearance, this account is provided under that disclaimer.
References: (click for full references)

Cella-Ribeiro, A., M. Hauser, L.D. Nogueira, C.R.C. Doria, and G. Torrente-Vilara. 2015. Length-weight relationships of fish from Madeira River, Brazilian Amazon, before the construction of hydropower plants. Journal of Applied Ichthyology 31:939-945.

Heinrichs-Caldas, W., and V.M.F. de Almeida-Val. 2021. Hypoxia tolerance in two amazon cichlids: mitochondrial respiration and cellular metabolism adjustments are the result of species environmental preferences and distribution. Fish Physiology and Biochemistry 47:1759-1775.

Hill, J.E., and Q.M. Tuckett. 2018. Abiotic and biotic contributions to invasion resistance for ornamental fish in west-central Florida, USA. Hydrobiologia 817:363-377.

Kaur, J. 2022. Morphological and osteological variation in cichlids (Perciformes: Cichlidae). M.S. Thesis, University of Alberta, Canada.

Kullander, S.O., 2003. Cichlidae (Cichlids). p. 605-654. In R.E. Reis, S.O. Kullander and C.J. Ferraris, Jr. (eds.) Checklist of the Freshwater Fishes of South and Central America. Porto Alegre: EDIPUCRS, Brasil.

Kullander, S.O., and A.M.C. Silfvergrip. 1991. Review of the South American cichlid genus Mesonauta Günther (Teleostei, Cichlidae) with descriptions of two new species. Revue suisse de zoologie 98:407–448.

Pires, T.H.S., D.F. Campos, C.P. Röpke, J. Sodré, S. Amadio, and J. Zuanon. 2015. Ecology and life-history of Mesonauta festivus: biological traits of a broad ranged and abundant Neotropical cichlid. Environmental Biology of Fishes 98:789-799.

Röpke, C.P., E. Ferreira, and J. Zuanon. 2014. Seasonal changes in the use of feeding resources by fish in stands of aquatic macrophytes in an Amazonian floodplain, Brazil. Environmental Biology of Fishes 97:401-414.

Röpke, C.P., S.A. Amadio, K.O. Winemiller, and J. Zuanon. 2016. Seasonal dynamics of the fish assemblage in a floodplain lake at the confluence of the Negro and Amazon Rivers. Journal of Fish Biology 89:194-212.

Sazima I., Machado F.A. 1990. Underwater observations of piranhas in western Brazil. Environmental Biology of Fishes 28:17–31.

Severo-Neto, F. and O. Froehlich. 2015. Cleaning behaviour of the cichlid Mesonauta festivus in the Pantanal wetlands: evidence of a potential freshwater cleaning station. Marine and Freshwater Behaviour and Physiology 49:63-68.

Other Resources:

Author: Brown, M.E.
Revision Date: 3/4/2025

 Citation Information:
Brown, M.E., 2026, Mesonauta festivus (Heckel, 1840): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=3889, Revision Date: 3/4/2025, Access Date: 1/12/2026

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.

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Citation information: U.S. Geological Survey. [2026]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [1/12/2026].

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