First record of Croaking Gourami Trichopsis vittata (Cuvier, 1831) from West Bengal, India

: The Croaking Gourami Trichopsis vittata (Cuvier, 1831) is a native fish to southeastern Asia and Sundaland, with introduction reports from the USA, Philippines, and many other countries including India. In India, this species was first reported from Chembarampakkam Lake situated in Chennai during the year 2015. This study reports the presence of this fish for the first time in the Magra Beel, a wetland in the district of Nadia, West Bengal, in 2021, 2022, 2023. The laboratory evaluated the fish samples taken from the marsh to determine their fin ray counts and morphometric data. The results identified the species as T. vittata and supported previous research.

Trichopsis vittata (Cuvier, 1831), known as Croaking Gourami in the ornamental fish trade, is a small airbreathing osphronemid fish, reported as native from Java, Borneo, Sumatra, Peninsular Malaysia, Thailand, and the Mekong basin in Cambodia, Laos, and Viet nam (Kottelat 1985;Baird et al. 1999).The species is an obligate airbreathing fish that prefers to live in shallow sluggish or standing-water habitats with abundant vegetation (Rainboth 1996).It can survive in brackish water up to 20 ppt salinity, and in temperatures down to 7.2 0 C (Schofield & Schulte 2016).It feeds on small planktonic crustaceans and insect larvae (Rainboth 1996).This species comprises more-extended filamentous anal-fin rays extending almost to the tip of the caudal-fin and also possesses three dark lateral stripes on the body.A typical dark spot is present above the pectoral fin of the fish as a unique identifying character.Unlike other osphronemid fishes, T. vittata is popularized for the production of audible sounds or "croaks" (Ladich & Yan 1998).
The non-native population of T. vittata has been documented from Myanmar and Bangladesh (Noren et al. 2017;Akash et al. 2018;Hossain et al. 2019).Literature depicts that in India T. vittata was first reported from the Chembarampakkam Lake situated in southern (Knight & Balasubramanian 2015); but its existence has not yet

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Abstract: The Croaking Gourami Trichopsis vittata (Cuvier, 1831) is a native fish to southeastern Asia and Sundaland, with introduction reports from the USA, Philippines, and many other countries including India.In India, this species was first reported from Chembarampakkam Lake situated in Chennai during the year 2015.This study reports the presence of this fish for the first time in the Magra Beel, a wetland in the district of Nadia, West Bengal, in 2021, 2022, 2023.The laboratory evaluated the fish samples taken from the marsh to determine their fin ray counts and morphometric data.The results identified the species as T. vittata and supported previous research.

First record of Trichopsis vittata from West Bengal
Dutta et al.

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Study Area and Methods
The fish samples were first collected on 1 August 2021 from the Magra Beel.The collection was done by using a hand held drag net as per the conventional method.Then in quest of other populations of fish, multiple field visits were done between August 2021 and July 2023 in different fishing points of the Magra Beel within a distance of 1.5 km (Point-1: Opposite to Bijra Primary School; Point-2: Concrete bridge at 3 number Magra Beel; Point-3: Kheya Ghat opposite to Birahi Union Tapashili Fishermen's Cooperative Society Limited office).The sampling sites of the Magra Beel are presented in Image 1.
After collection, the fish specimens were immediately preserved in 10% formalin for taxonomic study (Joshi et al. 2015).Different morphometric characteristics including total length, standard length, pectoral fin base length, pelvic fin base length, and anal fin base length were measured as per the conventional method and different meristic counts for dorsal fin rays, anal fin rays, Image 1.The sampling points during study in Magra Beel.
pectoral fin rays, pelvic fin rays were observed accordingly (Murdy & Shibkawa 2001).The preserved fish samples were submitted to the Fresh Water Fish Section of the Zoological Survey of India, Kolkata for identification and documentation.Some fish samples were subsequently transferred into 30%, 50%, and 70% ethanol for long-term preservation (Sterba 1962;Talwar & Jhingran 1991) for further study.

Morphometric and meristic characters
The collected samples have laterally elongated bodies with a standard length of 4.10 cm (Table 1).The dorsal fin originates far behind the base of the pectoral fin corroborating the previous findings of Hossain et al. presented in Table 1.The anal fin is comprised of multibranched fin rays with 6-8 spines and a few elongated filaments-like rays which are extended almost to the tip of the caudal fin.The dorsal fin of T. vittata has 2-4 spines, while the pelvic fin contains one spine followed by a filament and four rays.On the posterior half of the body, there are three longitudinal dark bands, which help to distinguish T. vittata from the related species T. schalleri and T. pumila (Noren et al. 2017).The fin ray counts are detailed in Table 1 and are consistent with the findings reported by Hossain et al. (2019).

Identification and cataloguing
After collecting the samples of fish from three different spots, the specimens were submitted to the Zoological Survey of India (ZSI) for identification and cataloguing.

Discussion
In this present study, T. vittata was found in a lower abundance than the other native fish species; but the overall count is sufficient to prove its strong adaptability to this new environment.T. vittata is an efficient invader that can survive in a small volume of water and can tolerate high pollution and low dissolved oxygen level conditions (Wongsiri, 1982).Knight & Balasubramanium (2015) reported that in India T. vittata may compete for niche space with native species such as Trichogaster lalius (Hamilton, 1822) and Spiketail Paradise Fish Pseudosphromenus cupnus (Cuvier, 1831).The negative effects of T. vittata may also include aggressive displacement of native species or it may also act as a vector for parasites or pathogens such as trematode, Euclinostomum heterostomum (Purivirojkul & Sumontha 2013).Thus, the spreading of T. vittata across the country over the years will affect the native fish biodiversity.Of late, the particular impact of this species on other indigenous fish species is currently unknown, therefore, further in-depth study regarding its biology, ecology, and inter-specific interactions among the non-native range in

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India are required at the earnest level.
The way of introduction of the fish species in the Magra Beel is not known.However, the most probable mechanism of introduction may be the release from the aquarium trade (Noren et al. 2017).As per the first recommendations of ZSI, Kolkata, "is an exotic species and distributed worldwide via aquarium trade.The specimen shows some variations from the description of Trichopsis vittata and may be a hybrid also.It needs further study based on freshly collected specimens for confirmation".Later on ZSI Kolkata identified and registered the specimen as Trichopsis vittata (Cuvier, 1831), family Osphronemidae [Regd No. ZSI FF 9935 dt. 24. 08. 2023].Deliberate aquaculture efforts could serve as a vector for invasion (Akash & Hossain 2018).Given that T. vittata has been previously reported in various rivers across Bangladesh (Noren et al. 2017), some of which are in close proximity to the state of West Bengal, it is plausible that this species could migrate to West Bengal via these river routes.
(2019) and Shefat et al. (2020).A thin black line is found below the eye (Noren et al. 2017).Stripes and black spots are visible on the fin of both sides of the body.The morphometric measurements including total length, standard length, pectoral fin base length, pelvic fin base length, and anal fin base length of the fish have been First record of Trichopsis vittata from West Bengal Dutta et al.Journal of Threatened Taxa | www.threatenedtaxa.org| 26 June 2024 | 16(6Trichopsis vittata collected from Magra Beel: A-Anal fin | B-Caudal fin | C-Pectoral fin | D-Dorsal fin.© Bakul Biswas.