Assessment of Invasive Armored Catfishes' (Pterygoplichthys disjunctivus and Hypostomus plecostomus) In-stream Habitat Use and Management in the San Marcos River


The objectives of this study are to 1) understand how invasive armored catfishes are using the spring-fed San Marcos River; 2) estimate various demographic and population parameters including relative age, size, and species of armored catfishes; and 3) evaluate effectiveness of current suppression efforts taking place in the San Marcos River.

Study Area

Upper reaches of the San Marcos River, San Marcos, Texas

Project Period

2017 – 2018


The United States is home to over 2100 non-native species introduced via a variety of methods including, but not limited to, aquarium dumping, intentional stocking, biological control attempts, and secondary release. The state of Texas is host to eight registered invasive species of fishes; including two species of non-native South American armored catfishes, the vermiculated sailfin catfish (Pterygoplichthys disjunctivus) and the sucker mouth catfish (Hypostomus plecostomus). These non-native grazers are known to have significant impacts on the ecosystems they invade, on both trophic levels and general ecosystem functionality- vegetation distribution, river bank shape and erosion rates. These armored catfishes have established populations in the spring-fed San Marcos River watershed in San Marcos, Texas. The San Marcos River is home to several endangered species of flora and fauna, including Texas Wild Rice. Little work has been done to understand the seasonal spatial movement and habitat utilization of non-native catfishes, nor on the effectiveness of employed removal methods to stop this particular biological invasion.

Publications and Presentations

Warner, K. 2018. Instream Habitat Use and Management of Invasive Armored Catfishes in the Upper San Marcos River. University of Houston-Clear Lake, Houston.

Warner, K.J., Guillen, G., and Hardy, T. 2018. Instream habitat use of invasive armored catfishes in the Upper San Marcos River. Annual Meeting of the Texas Chapter of the American Fisheries Society, College Station, TX. Presentation.


  • Environmental Institute of Houston

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