Small but tough: What can ecophysiology of croaking gourami Trichopsis vittata (Cuvier, 1831) tell us about invasiveness of non-native fishes in Florida?

Abstract

Trichopsis vittata (Cuvier, 1831) is a small, freshwater gourami (Fam: Osphronemidae) native to southeast Asia. It was first detected in Florida in the 1970s and seems to have persisted for decades in a small area. In this study, we documented T. vittata's ecophysiological tolerances (salinity and low-temperature) and qualitatively compared them to published values for other sympatric non-native species that have successfully invaded much of the Florida peninsula. Trichopsis vittata survived acute salinity shifts to 16 psu and was able to survive up to 20 psu when salinity was raised more slowly (5 psu per week). In a cold-tolerance experiment, temperature was lowered from 24 °C at 1 °C hr -1 until fish died. Mean temperature at death (i.e., lower lethal limit) was 7.2 °C. Trichopsis vittata seems as tolerant or more tolerant than many other sympatric non-native fishes for the variables we examined. However, T. vittata is the only species that has not dispersed since its introduction. Species other than T. vittata have broadly invaded ranges, many of which include the entire lower third of the Florida peninsula. It is possible that tolerance to environmental parameters serves as a filter for establishment, wherein candidate species must possess the ability to survive abiotic extremes as a first step. However, a species' ability to expand its geographic range may ultimately rely on a secondary set of criteria including biotic interactions and life-history variables.

Life history strategies differentiate established from failed non‐native freshwater fish in peninsular Florida

“…Specific factors related to its success are unknown, although we speculate that its typical occurrence in ditches and ephemeral marshes and ponds and its habit of burying in sediments reduces its contact with native fishes important in biotic resistance. Croaking Gourami is also different from other successful non‐natives because of its small body size, tiny eggs, and lower degree of parental care (Leingpornpan et al, 2006; Schofield & Schulte, 2016). It is, however, one of the less successful species because it was known only from a small, localized population from the 1970s through 1990s and was considered extirpated by the 2000s following surveys at the known sites (Shafland et al, 2008; USGS, 2021).…”

“…It is, however, one of the less successful species because it was known only from a small, localized population from the 1970s through 1990s and was considered extirpated by the 2000s following surveys at the known sites (Shafland et al, 2008; USGS, 2021). In 2012, Croaking Gourami was found in a complex of canals, ditches and wetlands nearby, suggesting undetected persistence of the original population (Schofield & Pecora, 2013; Schofield & Schulte, 2016). The African Jewelfish Hemichromis letourneuxi , although embedded in the cluster of equilibrium strategists, is unique because of its small body size and rapid spread throughout south and central regions of Florida (Hill, 2016; Langston et al, 2010; Lopez et al, 2012).…”

Lower Lethal Temperatures for Nonnative Freshwater Fishes in Everglades National Park, Florida

“…We have previously tested the low‐temperature tolerance of several nonnative fish species (e.g., Schofield et al. ; Schofield and Huge ; Schofield and Schulte ), and this experiment followed those general methods. To prepare fish for the temperature challenge, they were moved from holding tanks to individual containers (plastic bins fitted with lids and bubbled air) that were placed on racks in a large (about 6.5 m × 3 m) walk‐in environmental chamber set to 24°C.…”

First records of Croaking Gourami, Trichopsis vittata (Cuvier, 1831) (Teleostei: Osphronemidae), from Myanmar and Bangladesh

“…However, T. vittata does not have any mechanism for long-distance dispersal, as it is non-migratory and does not have planktonic eggs or larvae, and non-human mediated spread is likely to be slow. In addition, it may locally be limited by life-history variables or interactions with the native biota, as seems to be the case with the population in Florida (Schofield and Schulte 2016).…”

“…Trichopsis vittata is found in shallow, slow-flowing or stagnant waters with abundant vegetation, such as rice fields, roadside ditches, and irrigation canals. It is able to survive in brackish water up to 20 psu salinity, and in temperatures down to 7.2 °C (Schofield and Schulte 2016). It feeds on small planktonic crustaceans and insect larvae (Rainboth 1996).…”