Length-weight relationships of 37 freshwater fish species from the Lefini river,middle Congo River basin (Republic of the Congo)

The present study reports on length-weight relationships (LWRs) for 37 of the most abundant fish species in the Lefini River basin, one of the largest right bank tributaries of the Congo River in the Republic of the Congo. The study area comprised 12 stations along 103 km of the river. Each station was sampled during March 2007 to August 2008 following standardized methods utilizing five monofilament gill nets of 10, 12, 15, 20 and 30 mm mesh size. Sample size, lengths, weights, LWRs, 95% confidence intervals of a and b, coefficient of correlation r² and growth type are provided for each species. Values of allometric coefficient b of the LWRs (W = aSL^b) ranged from 2.556 for Synodontis nigriventris to 3.363 for Brycinus poptae. These results represent the first study of length-weight relationships for fish species in a large affluent of the Congo basin as a whole.     

Length-weight relationships of six fish species from the Xiangjiang River in Guangxi region,China

This study aimed to estimate the parameters of length-weight relationships (LWRs) for six freshwater fish species that inhabit in the Xiangjiang River of Guangxi region, China. The specimens were sampled in April, July, and October 2014 and in January 2015 using electrofishing (CWB-2000P, China; 12 V import, 250 V export) and traps (mesh size 8.5 mm; length 200 m) at five sampling sites. For each sampling site, a trap was settled on one nearshore zone of the river for 24 hr, and the electrofishing was applied within 30 min from downstream to upstream with 200 m long. Standard length was measured (be accurate to 0.1 cm) and total weight determined (be accurate to 0.1 g) after preservation in formaldehyde (10%). The values for the parameter b of the length-weight relationships were estimated together with the coefficient of determination scores. In addition, this study provides a new tentative LWRs for the six species.     

Length-weight relationship of six small fish species from the Negro River basin in the Brazilian Amazon

The main objective of the study was to estimate the parameters of the length-weight relationship for six small fish species of lower Negro River basin. The fish were sampled using monofilament gillnets (20 × 2 m, mesh size 5 mm between knots), and landing net for 2 days of each month in September and December 2017 and February, March and April 2018. The gillnets were placed in the river twice a day, in the morning (9–11 a.m.) and the afternoon (3–5 p.m.). Total length and total weight were measured to a precision of 0.1 cm and 0.01 g, respectively. The parameters a and b of the equation WT = a.LT^b were estimated.     

Length-weight relationships of fish species from oxbow lakes on the floodplain of the middle Purus River in western Brazilian Amazon

The length-weight relationship (LWRs) was estimated for eight fish species collected from oxbow lakes on the floodplain of the middle Purus River in western Brazilian Amazonia in January, May, and September 2012. The specimens were collected using 12 gillnets (80 m in length × 4 m in height, meshes of between 1.5 cm and 12.0 cm), which were set during both diurnal and nocturnal periods. The species had allometric coefficients (b) of between 2.92 and 3.37, and correlation coefficients (r²) ranging from 0.954 to 0.993 and we highlight that the work presents new data for literature.     

Length–weight relationship of seven fish species from the temporary habitat,Pantanal wetland,Brazil

The length–weight relationships (LWRs) were estimated of seven fish species from 22 localities in the Pantanal wetland between Mach 2006 and April 2011. Fish were sampled using seven gill nets (20 × 1.5 m; mesh size: 12, 15, 18, 20, 25, 30 and 50 mm between opposing knots) and throw traps (made of 1 m³ metal cubes, covered by a 1.5 mm nylon mesh). Standard length and weight were measured and used to calculate the LWR parameters. Values for parameter b varied from 2.87 (Apistogramma borellii) to 3.29 (Hoplerythrinus unitaeniatus) and, such values are within the expected range.     

Length-weight relationship of 12 species of freshwater fish caught in the middle and lower stretches of the Negro River basin,Brazilian Amazon

This study aimed to estimate the parameters of the length-weight relationship for 12 freshwater fish species that inhabit lakes in the Negro River basin (Amazonas state, Brazil). The fishes were sampled using gillnets (15 × 2 m, mesh size 30–100 mm between knots), during the hydrologic cycle: low water (dry), flooding, high water (flood), and receding water, from 2008 to 2010, 2012 and 2013. The gillnets were placed in the lakes with a standardized period of 24 hr, with fish removal occurring every 12 hr (2010 to 2010) and 6 hr (2012 and 2013). Measurements were taken for standard length (SL – 0.1 cm precision) and total weight (TW – 0.1 g precision). The parameters a and b of the equation WT = a.LT^b were estimated. This study also provides new data on of maximum lengths for three species.     

The length-weight relationship of four fish species captured in the Ibicuí River,southern Brazil

Length-Weight relationship (LWRs) were estimated for four fish species occurring in the Ibicuí River drainage basin, southern Brazil. Samples were captured monthly during the spring and summer seasons (October 2018 to March 2019). The fish were caught with gillnets of different meshes (15, 20, 25, 30, 40 mm between adjacent nodes) and a trawl net (5 mm mesh between adjacent nodes) Eighteen excursions were realized in three sites, with a length of approximately 100 km, in third-order flux, all distributed in sub-basin Ibicuí River. The captured tools were installed at the end of the day (6 p.m.) and removed around 6 a.m. the next day. The present study provides the length-weight relationship for four species (Astyanax dissensos, Galeocharax humeralis, Hypostomus roseopunctatus e Hypostomus uruguayensis).     

Length-weight relationships of six Nemacheilid fish species (Teleostei: Cypriniformes) from different rivers of Manipur,India

The length-weight relationships (LWRs) of six Nemacheilid species (Schistura chindwinica, S. fasciata, S. khugae, S. minuta, S. reticulata and S. rubrimaculata) have been analyzed. Fish samples were collected on quarterly basis from March 2018 to February 2019. Sampling was performed using cast nets (mesh size 5–10 mm; about 50 sq m area covered each time and water depth was 4 ft approx.), and electrofishing (Ultrasonic Inverter Electro Fisher, 24 volts, 4 m) in the day time. The total length (TL) of individual fish was measured to 0.1 cm with a digital caliper and body weights (BW) were measured to 0.001 g with digital electronic balances. The parameters for the LWR equations were calculated, and the respective statistics such as the 95% confidence interval for parameters “a” and “b” are provided as well as the coefficient of correlation. For five species a new maximum total length has been documented.     

Length‐weight relationship of three cichlid species in a stream in southwestern Amazon,Brazil

The paper investigates the length‐weight relationship of three cichlids species for the southwestern Amazon, Acre state. The individuals were collected at five sites during one year among august/2016 and june/2017 in Quinoá stream (10°06′03.33″S/67°40′11.50″W). The individuals were collected using: seine net, 6 m length, 2.25 high, and mesh size 5 mm, two dip nets, 5 mm mesh, 30 cm width, and 50 cm in length and two sieve with 5 mm mesh, 50 cm width, and 80 cm in length. The results show that one species presented positive allometric growth (Aequidens tetramerus) and the others negative allometric growth (Apistogramma acrensis and Crenicichla semicincta).     

Length-weight relationship of fish species captured around an artificial offshore reef (northern Rio de Janeiro,Brazil)

The present work provides length-weight relationships (LWRs) for fish species captured around artificial offshore reef deployed 5 km from Guaxindiba Port, northern Rio de Janeiro, Brazil. The fish were captured during two sampling periods each year between 1996 and 2017 using bottom gill nets (25 m_length × 3 m_depth; 30 mm mesh). The fish were kept on ice and the biometric data, including total length (cm) and total wet weight (g) were determined in the laboratory. A total of 16 species belonging to 10 families were analyzed with Sciaenidae being the species richest family (5 spp) in the samples. The new value of LWRs for Sphyraena guachancho and new maximum sizes recorded for seven species highlight the scarcity of information on biological aspects of South America coastal fishes. These LWRs should assist fisheries scientist and managers to complement their further studies of population parameters to improve management decisions.     

Length-weight relationships for seven endemic fish species from streams of the last two large remaining dam-free tributaries of the Upper Paraná River Floodplain in the Paraná State,Brazil

This study reports the length-weight relationships (LWR) for seven endemic fish species from streams in the Ivaí (Characidium heirmostigmata, Corydoras lacrimostigmata, Curculionichthys oliveirai, Hisonotus pachysarkos, and Cambeva horacioi) and Ivaí and Piquiri (Apareiodon vladii and Planaltina kaingang) River basins, Paraná State, Brazil. Fish specimens measured and weighed were collected between November 1994 and July 2019, fixed with 10% formalin, and are preserved in 70% alcohol. Measurements were done for standard length (SL—0.1 cm precision) and total weight (TW—0.01 g precision). All coefficient of allometry obtained is within the general range for fishes representing useful tentatives for LWR parameters. We highlight the importance of information about the biology of the endemic fish species in a crucial area for the biodiversity conservation of the Upper Paraná River system.     

Length-weight relationships of five fish species from Brazilian Amazon coast hotspot estuaries

The length-weight relationships (LWR) were estimated for five fish species from the Golfão Maranhense, Brazilian Amazon littoral region. Samplings were performed in August 2016, during the dry season, using trawl net with 6.0 m length by 3.0 m width (trawl mouth opening of 6.0 m²) and 1.0 cm mesh size between opposite knots. This study registers LWR for Anchoviella elongata and Gobioides broussonnetii and the estimated LWR for Aspredo aspredo and Aspredinichthys filamentosus covers a wider size range. Moreover, it is presented maximum length values for A. elongata and Sphoeroides greeleyi.     

Cichlid Fishes from the La Plata Basin. Part IV. Review of the Apistogramma Species, with Description of a New Species (Teleostei, Cichlidae)

Apistogramma inconspicua sp.n. is described from the Rio Candclaria in the Rio Guaporé drainage in Bolivia, and recorded also from Cáceres on the Rio Paraguay in Brazil. The new species is closely related to the Paraguayan species A. commbrae (Regan) and an undescribed species in the Guaporé drainage system. These species share a specialized feature in the colour pattern, viz. an expanded vertical bar on the caudal peduncle which it confluent with the caudal spot. The now presumably complete record of Paraguayan Apistogramma species allows an analytical key to be given. Of the additional species, A. borellii (Regan) and A. trifasciata (Eigenmann & Kennedy) represent two distinct lineages. Apistogramma pleurotaenia (Regan) is probably a La Plata basin species, although no localities are known, and its relationship remain obscure. The assemblage of Paraguayan Apistogramma species reflects the heterogeneity of the Paraguayan cichlid fauna as a whole.     

Length-weight relationships of eight fish species from the Hailang river,China

The present study reports the length-weight relationships (LWRs) for eight fish species sampled in Hailang River, a left-bank tributary of the Mudan River in Northeast China. The fishes were collected from April to October bimonthly 2017 by electrofishing (fishing 2 kilometers along the river and within 5 meters from the bank) and netting (drift gillnet: mesh size 2 cm × 3 cm; 200 m net length). The specimens were weighed (nearest 0.1 g) and measured (nearest 0.1 cm) in the laboratory. This study provides an update in maximum lengths for five species.     

Length-weight relationship of 74 fish species caught in the continental coast of Ecuador

This work analysis the length-weight relationships for fish species captured by artisanal fishery along the continental coast of Ecuador. Fishermen used the following fishing gear: beach seine nets (5.1–31.8 mm), shrimp trawl nets (21.8–31.8 mm) and bottom gill nets (54.1–203.2 mm). Sampling took place during the years 2012 and 2014. Frequency of sampling was monthly, and it was completed systematically from Southern toward Northern Provinces. Length-weight relationship (LWR) was realized by the power model (y = a × x^b), for species with a bivariate dataset >70. A total of 59 commercial and 15 non-commercial species were registered. For 74 species, our analysis including a higher total length not reported in LWR estimates previously. The determination coefficient (r²) value was always above 0.95.     

Length‐weight relationships for five freshwater fish species from the Utinga State Park,Northeast Amazon,Brazil

Length–weight relationships (LWR) were estimated for five most abundant fish species occurring in the Utinga State Park within the metropolitan area of Belém, State of Pará, Northern Brazil. Data were obtained from specimens of Curimata knerii (n = 75), Gasteropelecus levis (n = 54), Hemigrammus rodwayi (n = 82), Hyphessobrycon bentosi (n = 69), and Pristobrycon calmoni (n = 76) collected in July 2013 with seines (1.5 mm mesh), sieves (1 mm mesh), and gill nets (40–120 mm mesh) in the main waterbodies. All LWRs are novel for science, increasing knowledge on biological information of the Neotropical freshwater fish.     

Length-weight relationships of fish species from the Stung Russei Chrum River basin,Kingdom of Cambodia

This study evaluated the length-weight relationships (LWRs) for three teleost fish species sampled from the Stung Russei Chrum River basin, Kingdom of Cambodia. The fish were collected during two dry seasons (April 2019 and November 2019) and one rainy season (October 2018) using monofilament trammel nets (2–12 cm mesh size), cast net (mesh size 2 cm) and scoop-nets (mesh size with 0.3 cm). Results showed that all fitted regressions were highly significant and the coefficients of determination (r²) were high. This study expanded the value of maximum total length for Cyclocheilichthys apogon and Poropuntius laoensis while reported the wider ranges of total mass for Poropuntius laoensis. Moreover, our present study also provided the novel LWRs records for Hemibagrus filamemtus.     

Length-weight relationship of 16 fish species from the Negro River basin (Amazonas state,Brazil)

This study aimed to estimate the parameters of length-weight relationship for 16 freshwater fish species that inhabit the Aracá and Demeni Rivers, which are two tributaries of the Negro River (Amazonas state, Brazil). The fishes were sampled using gillnets (15 × 2 m, mesh size 30–120 mm between opposite knots), during 6 days each year, in April 2016, November 2018 and April 2019. The gillnets were placed in the river twice each day; in the morning (5–9 a.m.) and in the evening (5–9 p.m.), with a standardized time of 4 hr. Measurements were taken for standard length (SL – 0.1 cm precision) and total weight (TW – 0.01 g precision). The parameters a and b of the equation W_T = a.L_T^b were estimated. This study also provides new data on of maximum lengths for six species, namely, Argonectes longiceps, Hemiodus atranalis, Chalceus erythrurus, Astrodoras asterifrons, Trachydoras steindachneri and Acarichthys heckelii.     

Length-weight relationships of four fish species from the Yalong River,China

Parameters of the length-weight relationship (LWR) were estimated for four fish species [Beaufortia szechuanensis (Fang, 1930), Claea dabryi (Sauvage, 1874), Percocypris pingi (Tchang, 1930), and Yunnanilus sichuanensis Ding, 1995] from the Yalong River. Samples were collected seasonally from June 2018 to July 2019, using various fishing gears [set nets (mesh: 1.5 × 2.0 cm), hook, drift gill nets (three mesh sizes: 1.0; 2.0; 3.0 cm) and electro fishing]. Two new maximum standard length were recorded for C. dabryi and P. pingi.     

Length-weight relationships of three Clupeiformes species from the Southeast coast of India,Bay of Bengal,Eastern Indian Ocean

This study deals with the length-weight relationships (LWRs) of three commercially important marine fishes belonging to the family Clupeidae from the major landing centers in Tuticorin, Mandapam, Thondi, Nagapattinam and Chennai in southeast coast of India. Monthly sampling were done at the respected landing centers from June, 2018 to April, 2019 from the commercial trawlers (with cod-end mesh size of 25–35 mm) and gill netters (with different mesh size vary from 20 to 170 mm). The estimated ‘b’ values ranged from 3.1215 (Sardinella albella) to 3.1819 (Amblygaster clupeoides) and ‘a’ values varied from 0.0059 (A. clupeoides) to 0.0074 (S. albella). The study also provides a new maximum total length (TL_max) for two species A. clupeoides and Sardinella fimbriata.