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Categorizing Introduced Fishes Collected from Public Waters
Paul L. Shafl and, Kelly B. Gestring, and Murray S. Stanford

Southeastern Naturalist, Volume 7, Number 4 (2008): 627–636

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2008 SOUTHEASTERN NATURALIST 7(4):627–636 Categorizing Introduced Fishes Collected from Public Waters Paul L. Shafl and1,*, Kelly B. Gestring1, and Murray S. Stanford1 Abstract - Introduced plants and animals have been a prominent worldwide environmental issue for decades; however, considerable debate and confusion remain over how to list and otherwise categorize these species. This paper describes a process for categorizing exotic freshwater fishes that have been found in public waters. The basis of this process has been used by the Florida Fish and Wildlife Conservation Commission for nearly 30 years. Reproducing exotic fishes are grouped into three subcategories (established, possibly established, and localized) using species-specific biological and population characteristics resulting in a list that is helpful for prioritizing research and management activities. The purpose of this paper is to stimulate interest in standardizing processes for categorizing introduced species based on how well they adapt to new environments. Introduction Exotic fishes have long been a prominent environmental issue, although the general awareness of this issue has never been more widely recognized than it is today. A recent Internet search for “exotic fish problems” generated more than 1.17 million responses. While this has been a high-priority issue within the fisheries profession for decades, considerable confusion and debate remains about how to define terminology, list, categorize, or otherwise summarize the status of introduced species. A simple list of exotic species collected from a given area sometimes over-estimates their importance because, all things being equal, a long list of species represented by the collection of single individuals can have fewer consequences than a much shorter list of highly successful species (i.e., those that are reproducing, abundant, and widespread). Relatively few exotic species become established (i.e., permanent residents) after being introduced, and even fewer become abundant and widespread (Williamson 2006), although some that do have had serious effects (FL ISWG 2003, Moyle and Light 1996, Simberloff and Gibbons 2004, Trexler et al. 2000). This paper describes a process for categorizing exotic freshwater fishes found in public waters that also provides some guidance for setting management priorities. This categorization process initially requires species-specific field assessments. Once determined, the general status of each species can be monitored and updated with minimal effort. Moreover, if such a standardized process is adopted by others, it would make comparisons of independently generated species listings from different geographic areas more objective. This basic categorization process has been used by the Florida Fish and Wildlife Conservation Commission for nearly three decades (Shafland 1979, 1986, 1996; Shafland et al. 2008). 1Non-Native Fish Laboratory, Florida Fish and Wildlife Conservation Commission, Boca Raton, FL 33431. *Corresponding author – paul.shafl 628 Southeastern Naturalist Vol. 7, No. 4 In this paper, we categorize 55 Florida exotic freshwater fishes into two main categories: reproducing and non-reproducing fishes (Appendix 1; Shafl and et al. 2008). The reproducing fishes are divided into three subgroups (established, possibly established, and localized), while the non-reproducing introduced fishes are divided into two subgroups (formerly reproducing and species of interest). Introduced Species Categories Reproducing fishes Established fishes. Species are established if they: a) can be consistently collected from large or interconnected public waters from which they cannot be practically eliminated, b) are present in sufficient abundance to indicate the population has been stable or expanding for several years, and c) no species-specific environmental limiting factor exists that could reasonably cause their demise (e.g., water temperature, drought). All 23 established exotic freshwater fishes in Florida, except Cyprinis carpio Linnaeus (Common Carp), are from tropical or subtropical areas. As a result, the primary factor limiting the distribution of most exotic fishes in Florida is their inability to withstand low water temperatures (Shafl and and Pestrak 1982). For example, Cichla ocellaris Bloch & Schneider (Butterfl y Peacock Bass) has the highest lower-lethal temperature (15 oC) of all established exotic fishes, and its core populations are restricted to the uniquely warmed waters of metropolitan southeast Florida canals (Shafl and 1995). Many of these canals periodically approach or even drop below 15 oC; hence, exotic freshwater fishes with lower-lethal temperatures >15 oC are unlikely to become established in Florida. Possibly established fishes. Possibly established fishes are those species that have not attained sufficient success to be considered permanent residents. These fishes are known or believed to have reproduced, but are so limited in range or abundance that one could reasonably expect they might eventually disappear (e.g., see Ancistrus sp. [Bristlenosed Catfish] and Tilapia buttikoferi Hubrecht [Hornet Tilapia] subsections below). Localized fishes. Localized species are those reproducing in confined and isolated areas from which they might be eliminated (e.g., see Metynnis sp. [Silver Dollar] subsection below). Non-reproducing fishes Formerly reproducing fishes. Formerly reproducing fishes include those that have reproduced, but since disappeared or were intentionally eradicated. Species of interest. In the past, we listed every species of exotic freshwater fish collected, even if only once and as a single specimen. This practice was discontinued because such reports were often impossible to verify. We now use a much smaller category entitled “species of interest” which includes fishes that have been collected multiple times without evidence of reproduction, appear to be natural hybrids, or are of interest for some other specific reason. 2008 P.L. Shafl and, K.B. Gestring, and M.S. Stanford 629 Other listing criteria Criteria used to differentiate the five subcategories of exotic fishes require considerable data and field observations, and are specific and progressive, but non-quantifiable. Better field data enhances decision-making, but there remains some subjectivity in this process. This subjectivity is unavoidable because the status of each fish is a unique compilation of situation- specific life-history attributes (e.g., physiochemical limiting-factors) and population parameters (e.g., the species’ distribution, abundance, size structure, and persistence). Hence, when an exotic fish does not fit neatly into one of the five subcategories, it is generally placed in the less speculative group (i.e., the one easiest to independently verify). Examples of species that do not fit neatly into a specific subcategory are Heros severus Heckel (Banded Cichlid) and Theraps melanurus x T. zonatus? (Theraps hybrid; see below). The amount of time between the first indication an exotic species is reproducing and when it is considered established is based on a variety of factors. For example, species may remain categorized as possibly established for 10–20 years if their introduced population remains minimally successful (e.g., see subsection on Cichlasoma meeki Brind [Firemouth Cichlid]), or if they are likely to be killed by exceptionally cold winters that only occur every 10–20 years. However, if a species is widespread, abundant, has no area-specific limiting factors (e.g., thermal tolerances), and is represented by multiple year classes in a large water body when first encountered, it can be categorized as established almost immediately (e.g., Channa marulius Hamilton [Bullseye Snakehead]; see below). Possibly established, species of interest, and localized species are generally given high research and management priorities when first discovered because this is when eradication or other intervention activities have the best opportunity to succeed. Established species generally pose greater long-term ecological risk and socioeconomic harm. Thus, established species are typically given higher long-term research and management priority than those that that are less successful (i.e., those categorized as possibly established, localized, or species of interest). Using these criteria, the number of established species should never decrease since established is used synonymously with permanent. Similarly, the number of formerly reproducing species should never decrease unless one of these species is re-introduced and starts reproducing again. If a new reproducing population of a species listed as formerly reproducing were discovered, it would be removed from this category and added to either the established, possibly established, or localized category. In this paper, “standardized” electrofishing samples refer to electrofishing samples that have been standardized within specific waterways by transects, pedal-minutes (i.e., number of minutes that an electrical current is applied to the water), time of year, and time of day (daylight versus nighttime). Finally, the categories and subcategories used here are based largely on the terminology adopted by the American Fisheries Society at its 1984 Annual Executive Committee Meeting (Providence, RI) and published by Shafl and and Lewis (1984). 630 Southeastern Naturalist Vol. 7, No. 4 The most important aspect of this categorization process is the mandatory field-verification needed to determine the status of all reproducing species. These field-verifications are based on non-random, area-specific samples of existing or previously reported populations. The placement of these species into specific categories is based on the Florida Fish and Wildlife Conservation Commission’s recent collections and observations, unless otherwise specified. When categorizing these species, the specific method used for collecting them is generally unimportant because a species’ population characteristics (e.g., number and sizes present) determine the category it is placed in. Nonetheless, specific collection methods are reported in order to assist other scientists interested in independently verifying or updating a species’ status. Some Species-specific Applications Eight exotic fishes that have been collected from Florida’s public waters were selected to illustrate this categorization process. These are: Banded Cichlid Since 1993, Banded Cichlid have been occasionally observed and collected in Snapper Creek (C-2) and Tamiami (C-4) canals (Shafl and 1996). In June 2005, 10 Banded Cichlid were observed and two collected by electrofishing, and in May 2006, more than 20 were observed, though only two were collected (the Banded Cichlid is very difficult to electrofish). A pair of spawning Banded Cichlid guarding young has been observed in Snapper Creek (Leo Nico, United States Geological Survey [USGS], Gainesville, FL, pers. comm., October 2006), and juveniles (ca. 25 mm TL) have been collected from the L-30 Canal in Miami-Dade County (Joel Trexler, Florida International University, Miami, FL, pers. comm., May 2005). These collections and observations provide sufficient evidence Banded Cichlid is reproducing; hence, it is listed as possibly established. The Banded Cichlid has very slowly and steadily increased since it was first collected in 1993; and, though not yet abundant, it seems its designation will ultimately be changed to established assuming it continues to increase, survives a cold winter, or its lower-lethal temperature is determined to be <15 oC. Bristlenosed Catfish Since January 2001, 11 Bristlenosed Catfish (122–215 mm TL) were electrofished and three others observed in the same general area of Tamiami Canal. The smallest Bristlenosed Catfish was recently collected, indicating this species had reproduced; therefore, it is now categorized as possibly established even though only a total of 14 specimens have been collected or observed. Bullseye Snakehead The first Florida collection of Bullseye Snakehead was in October 2000. Initial sampling indicated this species had been present in the Cypress Creek Canal system for at least 2–3 years. Based on their abundance, presence of multiple size classes, distribution throughout a 155-km2 area when first documented, and its lower-lethal temperature of 10 oC (P.L. Shaffl and, K. B. Gestring, and M.S. 2008 P.L. Shafl and, K.B. Gestring, and M.S. Stanford 631 Stanford, unpubl. data), the Bullseye Snakehead was categorized as established shortly after its discovery. Firemouth Cichlid Comfort Canal in Miami-Dade County historically contained the only known reproducing population of Firemouth Cichlid in an open waterway (Hogg 1976). Access to this short, shallow canal (length = 6 km, average depth = ca. 2 m) is limited, and therefore it was infrequently sampled. Targeted sampling in 2005 captured none and no Firemouth Cichlid have been observed, collected, or reported elsewhere in Florida for >10 years. Based on these observations, the Firemouth Cichlid status was changed from possibly established to formerly reproducing. Hornet Tilapia In 2005, the first Florida-collected Hornet Tilapia (163 mm TL, 210 g) was electrofished from the Tamiami Canal, and 26 more have been collected since. Twenty-three of these were collected from Snapper Creek Canal, and the four others from the intersecting Tamiami Canal. Although only 27 (71–338 mm TL, 8–1140 g) Hornet Tilapia have been collected to date, the presence of adults and juveniles indicate this fish has reproduced; it is now categorized as being possibly established. Silver Dollar A total of 23 Silver Dollar (68–175 mm TL) were electrofished, and at least 13 others observed from two interconnected, but otherwise isolated, Martin County ponds since January 2005. In three 2005 samples, 6–14 Silver Dollar were collected, but in 2006, two samples yielded only one Silver Dollar, and only one was collected in a single 2007 sample. After the Silver Dollar was discovered, these ponds (ca. 16 ha) were treated with herbicides and the amount of vegetation was greatly reduced, which increased the Silver Dollar’s vulnerability to resident predators. These data suggest Silver Dollar reproduced, but subsequently decreased in abundance, and may ultimately disappear without having to spend an estimated $100,000 to renovate these ponds with a fish toxicant. This species is listed as localized, although it may not survive, in which case it would be placed in the formerly reproducing category. Theraps hybrid Twenty-four specimens of a Theraps hybrid (133–321 mm TL; 50–810 g) have been electrofished from Biscayne Canal since 2001. The overwhelming majority of Theraps hybrids collected and observed have been adults, and until recently it seemed possible this fish had not reproduced. However, in October 2006, two smaller specimens (133 and 136 mm TL) were collected indicating reproduction had likely occurred. This fish is now considered possibly established. Grass Carp The triploid Ctenopharyngodon idella (Valenciennes in Cuvier and Valenciennes) (Grass Carp) is listed as a species of interest since it continues to be legally introduced widely in Florida to control aquatic vegetation, 632 Southeastern Naturalist Vol. 7, No. 4 the results of which have generally been favorable. Regardless of the circumstances, the legal introduction of an exotic species is one of the most controversial management practices that can be proposed today. Although this species has never reproduced in the wild in Florida, it remains categorized as a species of interest. Discussion Exotic species and their effects have emerged as one of the prominent environmental issues of our times. Mack et al. (2000) state the “failure to address the issue of biotic invasions could effectively result in severe global consequences, including the wholesale loss of agricultural, forestry, and fishery resources in some regions, disruption of the ecological processes that supply natural services on which human enterprise depends...” Similarly, Pimental et al. (2005) state that “invading alien species in the United States cause major environmental damages and losses adding up to almost $120 billion per year.” Given such widely accepted and often repeated assertions within the scientific community, it seems worthwhile to develop standardized methodology and terminology for categorizing these species on the basis of rigorous post-introduction field evaluations. One of the simplest means to categorize introduced species is “as either successful or unsuccessful, based on how they are doing today” (Peter Moyle, University of California, Davis, CA, pers. comm., April 2007). While such a system is useful to a point, it has some obvious limitations. For example, some confuse “success” as a measure of invasiveness (i.e., the more abundant and widespread an introduced species is, the more invasive it is), while others argue invasive “should not be used to connote negative environmental impact” (Ricciardi and Cohen 2007). The only other listing process similar to the one described here is the Web-based system produced by the United States Geological Survey (USGS). Strengths of the USGS method are inclusion of all exotic fauna, not just fish, and daily updating with information voluntarily provided by numerous sources. This highly interactive website ( is often used as a source of information inventorying introduced species within specific jurisdictions or areas of interest. The main differences between the USGS system and ours are that the USGS’ is not field-verified and it uses seven somewhat less stringently defined categories rather than the five recommended here. The seven USGS categories and criteria (Pam Fuller, USGS, Gainesville, FL, pers. comm., April 2007) are: 1. established—species that have reproduced and over-wintered, 2. locally established—species that have reproduced and over-wintered, but only in a small area such as a pond where eradication may be possible, 3. collected/reported—collected but not known to have reproduced, 4. failed—species never seen after an unspecified amount of time since being introduced, 5. stocked—species persists through repeated stockings, 6. extirpated—species died out on its own, and 7. eradicated—species no longer present through human intervention. 2008 P.L. Shafl and, K.B. Gestring, and M.S. Stanford 633 The most important limitation in the USGS process is that it is impossible for USGS personnel to verify the identification, location, and status of every species in every report it includes in its database. Field verification greatly enhances quality control, accuracy, and usefulness of such listings; however, this also requires a long-term commitment of personnel and funds by sponsoring agencies. Florida appears to be the only state or federal agency that currently maintains and field-verifies categorical listings of its exotic freshwater fishes using species-specific biological and population criteria. Other state and federal agencies apparently do not dedicate sufficient manpower and funding to maintain a dedicated field-verification program to assess the resident introduced fishes within their jurisdictions. Given the high priority introduced species research is receiving by these agencies and others, it seems the need for field verifications of such listings is more important now than ever before. The most important recent change in our categorization process is that the evidence needed for reproduction is less stringent (i.e., previously, evidence of reproduction had to be definitive). Now, when different size classes are collected from the same general area (no matter how few specimens are actually collected), the species is categorized as possibly established (see Bristlenosed Catfish, Hornet Tilapia, and Theraps hybrid accounts above). As a result, the possibly established category is now more inclusive and dynamic than before. There is a general consensus within the scientific community that introduced fishes can have serious ecological and/or socioeconomic consequences. Introduced species have also received an enormous amount of attention from numerous governmental and non-governmental organizations during the past 30–40 years. Thus, it seems universal standards for categorizing introduced species collected from public waters would contribute beneficially to our assessments and understanding of this important issue. Conclusion The basic process described for categorizing introduced fishes from public waters has been used by the Florida Fish and Wildlife Conservation Commission for nearly 30 years. This categorization process includes two main categories containing five relatively objective subcategories defined by species-specific biological and population-level characteristics. This process facilitates a wide variety of circumstances commonly associated with introduced species and uses field-verified data and observations to place each species into one of five biologically meaningful groups (i.e., established, possibly established, localized, formerly reproducing, and species of interest). This categorization process is not all-inclusive and does not fit every current or anticipated need; however, it offers a reasoned approach that could be amended or supplanted by others. Given the amount of interest in introduced species worldwide, adoption of a rigorous field-verified categorization process is important as it could help prioritize research needs and allow for more objective comparisons of independently generated introduced species assessments. 634 Southeastern Naturalist Vol. 7, No. 4 Acknowledgments We gratefully acknowledge Michael Allen, Charles Cichra, Walter Courtenay, Fred Cross, Donald Fox, Pam Fuller, Jon Fury, Scott Hardin, Jeff Hill, Robert Howells, Howard Jelks, Jeffrey Kline, Robert Kobza, Jerry Krummrich, William Loftus, Samuel McKinney, Leo Nico, Jenny Novak, William Smith-Vaniz, Joel Trexler, Craig Watson, and Paul Zajicek for their useful comments on various drafts of this manuscript. Literature Cited Florida Invasive Species Working Group (FL ISWG). 2003. Statewide invasive species strategic plan for Florida. Florida Department of Environmental Protection, Tallahassee, FL. 47 pp. Fuller, P.L., L.G. Nico, and J.D. Williams. 1999. Nonindigenous Fishes Introduced into Inland Waters of the United States. American Fisheries Society Special Publication 27. Bethesda, MD. 613 pp. Hogg, R.G. 1976. Established exotic cichlid fishes in Dade County, Florida. Florida Scientist 39(2):97–103. Mack, R.N., D. Simberloff, W.M. Lonsdale, H. Evans, M. Clout, and F.A. Bazzaz. 2000. Biotic invasions: Causes, epidemiology, global consequences, and control. Ecological Applications 10(3):689–710. Moyle, P.B., and T. Light. 1996. Biological invasions of fresh water: Empirical rules and assembly rules. Biological Conservation 78:149–161. Nelson, J.S., E.J. Crossman, H. Espinosa-Perex, L.T. Findley, C.R. Gilbert, R.N. Lea, and J.D. Williams. 2004. Common and Scientific Names of Fishes from the United States, Canada, and Mexico. Sixth Edition. American Fisheries Society Special Publication 29. Bethesda, MD. 386 pp. Pimentel, D., R. Zuniga, and D. Morrison. 2005. Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics 52:273–288. Ricciardi, A., and J. Cohen. 2007. The invasiveness of an introduced species does not predict its impact. Biological Invasions 9:309–315. Shafl and, P.L. 1979. Non-native fish introductions with special reference to Florida. Fisheries (Bethesda) 4(3):18–24. Shafl and, P.L. 1986. A review of Florida’s efforts to regulate, assess, and manage exotic fishes. Fisheries (Bethesda) 11(2):20–25. Shafl and, P.L. 1995. Introduction and Establishment of a successful Butterfl y Peacock fishery in southeast Florida canals. American Fisheries Society Special Publication 15:443–451. Shafl and, P.L. 1996. Exotic fishes of Florida—1994. Reviews in Fisheries Science 4(2):101–122. Shafl and, P.L., and W.M. Lewis. 1984. Terminology associated with introduced organisms. Fisheries 9(4):17–18. Shafl and, P.L., and J.M. Pestrak. 1982. Lower-lethal temperatures for fourteen nonnative fishes in Florida. Environmental Biology of Fishes 7(2):149–156. Shafl and, P.L., K.B. Gestring, and M.S. Stanford. 2008. Florida’s exotic freshwater fishes—2007. Florida Scientist 3:220–245. Simberloff, D., and L. Gibbons. 2004. Now you see them, now you don’t! Population crashes of established introduced species. Biological Invasions 6:161–172. Trexler, J.C., W.F. Loftus, F. Jordan, J.J. Lorenz, J.H. Chick, and R.M. Kobza. 2000. Empirical assessment of fish introductions in a subtropical wetland: An evaluation of contrasting views. Biological Invasions 2000 (2):265–277. Williamson, M. 2006. Explaining and predicting the success of invading species at different stages of invasion. Biological Invasions 8:1561–1568. 2008 P.L. Shafl and, K.B. Gestring, and M.S. Stanford 635 Appendix 1. List of exotic freshwater fishes collected from Florida fresh waters.1,2 I. REPRODUCING FISHES (n = 34) A. Established species (n = 23; permanent populations; i.e., populations unlikely to be eliminated by man or natural causes and from which individuals can be regularly collected). 1. Brown Hoplo Hoplosternum littorale Hancock Callichthyidae 2. Bullseye Snakehead Channa marulius Hamilton Channidae 3. Oscar Astronotus ocellatus Agassiz Cichlidae 4. Butterfl y Peacock Cichla ocellaris Bloch & Schneider Cichlidae Bass 5. Black Acara Cichlasoma bimaculatum Linnaeus Cichlidae 6. Midas Cichlid Cichlasoma citrinellum Gunther Cichlidae 7. Rio Grande Cichlid3 Cichlasoma cyanoguttatum Cichlidae Baird & Girard 8. Jaguar Guapote Cichlasoma managuense Gunther Cichlidae 9. Yellowbelly Cichlid Cichlasoma salvini Gunther Cichlidae 10. Mayan Cichlid Cichlasoma urophthalmus Gunther Cichlidae 11. African Jewelfish4 Hemichromis letourneuxi Sauvage Cichlidae 12. Blue Tilapia Oreochromis aureus Steindachner Cichlidae 13. Mozambique Tilapia Oreochromis mossambicus Peters Cichlidae 14. Blackchin Tilapia Sarotherodon melanotheron Ruppell Cichlidae 15. Spotted Tilapia Tilapia mariae Boulenger Cichlidae 16. Walking Catfish Clarias batrachus Linnaeus Clariidae 17. Common Carp Cyprinus carpio Linnaeus Cyprinidae 18. Suckermouth Catfish4 Hypostomus sp. Loricariidae 19. Vermiculated Sailfin Pterygoplichthys disjunctivus Weber Loricariidae Catfish 20. Orinoco Sailfin Pterygoplichthys multiradiatus Loricariidae Catfish Hancock 21. Clown Knifefish Chitala ornata Gray Notopteridae 22. Pike Killifish Belonesox belizanus Kner Poeciliidae 23. Asian Swamp Eel Monopterus albus Zuiew Synbranchidae B. Possibly established species (n = 9; species believed to be reproducing, but might eventually be eliminated by man or natural causes; i.e., populations are typically small, have limited distributions, and cannot consistently be collected). 1. Eartheater Geophagus sp. Cichlidae 2. Eastern Happy4 Haplochromis callipterus Gunther Cichlidae 3. Banded Cichlid Heros severus Heckel Cichlidae 4. Theraps Hybrid4 Theraps melanurus x T. zonatus? Cichlidae 5. Hornet Tilapia4 Tilapia buttikoferi Hubrecht Cichlidae 6. Nile Tilapia5 Oreochromis niloticus Linnaeus Cichlidae 7. Oriental Weatherfish Misgurnus anguillicaudatus Cantor Cobitidae 8. Bristlenosed Catfish Ancistrus sp. Loricariidae 9. Spotfin Spiny Eel4 Macrognathus siamensis Gunther Mastacembelidae C. Localized species (n = 2; a confined, reproducing population that might be eliminated by natural causes or by humans using available methods). 1. Silver Dollar Metynnis sp. Characidae 2. Variable Platyfish Xiphophorus variatus Meek Poeciliidae 636 Southeastern Naturalist Vol. 7, No. 4 II. NON-REPRODUCING FISHES (n = 21) A. Formerly reproducing species (n = 14; illegally introduced populations intentionally eliminated by humans indicated by an asterisk). 1. Climbing Perch Anabas testudineus Bloch Anabantidae 2. Croaking Gourami Trichopsis vittata Curvier Anabantidae 3. Siamese Fightingfish Betta splendens Regan Anabantidae 4. Twospot Ctenopoma Ctenopoma nigropannosum Anabantidae Reichenow 5. Trahira Hoplias malabaricus Bloch Characidae 6. Pirambeba* Serrasalmus humeralis Valenciennes Characidae 7. Firemouth Cichlid Cichlasoma meeki Brind Cichlidae 8. Convict Cichlid* Cichlasoma nigrofasciatum Gunther Cichlidae 9. Jack Dempsey Cichlasoma octofasciatum Regan Cichlidae 10. Threespot Cichlid* Cichlasoma trimaculatum Gunther Cichlidae 11. Redbelly Tilapia* Tilapia zillii Gervais Cichlidae 12. Guppy Poecilia reticulate Peters Poeciliidae 13. Green Swordtail Xiphophorus hellerii Heckle Poeciliidae 14. Southern Platyfish Xiphophorus maculates Gunther Poeciliidae B. Species of interest (n = 7; fishes collected multiple times without evidence of reproduction, possible natural hybrids, and/or are of interest for some other reason). 1. Black Pacu Colossoma macropomum Cuvier Characidae 2. Redbellied Pacu Piaractus brachypomus Cuvier Characidae 3. Cichlasoma Hybrid4 C. citrinellum x C. urophthalmus Cichlidae 4. Northern Snakehead Channa argus Cantor Channidae 5. Grass Carp Ctenopharyngodon idella Cyprinidae Valenciennes 6. Barred Bichir Polypterus delhezi Boulenger Polypteridae 7. False Siamese Shark4 Platytropius siamensis Sauvage Schilbidae 1Most names follow those recommended by AFS’ Committee on Names of Fishes (Nelson et al. 2004) and Special Publication No. 27 (Fuller et al. 1999). 2Definitions of exotic, established, possibly established, and transplanted follow those adopted by the American Fisheries Society at its 1984 Annual Executive Committee Meeting in Providence, Rhode Island; and published in Fisheries 9(4):17–18. 3Technically a transplant since its natural range encompasses a portion of southern Texas. 4Species not listed by AFS’ Committee on Names of Fishes (Nelson et al. 2004) or Fuller et al. (1999). 5Identification tentative as this fish may possibly be a hybrid.