Caudal Peduncle Length Research Articles

Comparative Analysis of Morphometric and Meristic Characters in Oreochromis niloticus (Linnaeus, 1758), Nile Tilapia across Diverse Ecological Zones in Nigeria

The present study investigated the comparative analysis of morphometric and meristic characteristics in Oreochromis niloticus (Linnaeus, 1758) from six lakes in different ecological zones across Nigeria. A total of 347 samples were collected. Twenty-nine morphometric characters were measured to the nearest 0.01 cm using Vernier calipers and nine meristic characters were counted in all the collected individuals. The results of the univariate analysis of variance (ANOVA) revealed that all observed morphometric and meristic characters were significantly different (P=0.05) across the study sites. Notably, O. niloticus from Asejire Lake had significantly higher values in all the morphometric characters. The multivariate analysis of variance (MANOVA) identified three morphometric and four meristic characters as the most discriminating traits among the studied populations. These findings align with previous research highlighting the utility of morphometric and meristic data in delineating fish populations based on habitat differences and genetic compositions. Significant differences in head-related (head length), swimming-related (anal fin length and caudal peduncle length), and feeding-related (both left and right gill raker) measurements further underscored environmental influences on morphological variation. The study suggests that ecological factors such as food availability and environmental conditions contribute to the observed variations. This research provides valuable insights into the population dynamics and adaptation strategies of O. niloticus in diverse aquatic environments across Nigeria

Effects of Different Cultivation Modes on Morphological Traits and Correlations between Traits and Body Mass of Crayfish (Procambarus clarkii).

In this study, juvenile crayfish hatched from the same population were cultured in different growing environments: pond (D1), paddy field (D2), and aquaculture barrel (D3), and fed for 60 days. Crayfishes were selected randomly, females and males, 50 tails each from six groups (D1-♀, D1-♂, D2-♀, D2-♂, D3-♀, D3-♂) to measure the following morphological traits: full length (X1), body length (X2), chelicerae length (X3), chelicerae weight (X4), cephalothorax length (X5), cephalothorax width (X6), cephalothorax height (X7), eye spacing (X8), caudal peduncle length (X9), and caudal peduncle weight (X10). We found that the coefficient of variation (CV) of X4 was the largest in each culture mode, and males (28.58%~38.67%) were larger than females (37.76%~66.74%). The CV of X4 of crayfish cultured in D1 and D2 was larger than that of D3. All traits except X8 were positively correlated with body weight (p < 0.05). After pathway analysis, we found that X4, X5, X7, and X10 were significantly correlated with the body weight of D1-♀; the equation was YD1-♀ = -29.803 + 1.249X4 + 0.505X5 + 0.701X7 + 1.483X10 (R2 = 0.947). However, X2, X4, and X6 were significantly correlated with the body weight of D1-♂; the equation was YD1-♂ = -40.881 + 0.39X2 + 0.845X4 + 1.142X6 (R2 = 0.927). In D2-♀, X1, X4, X5, and X10 were significantly correlated with body weight; the equation was YD2-♀ = -12.248 + 0.088X1 + 1.098X4 + 0.275X5 + 0.904X10 (R2 = 0.977). X4 and X5 played a major role in the body weight of D2-♂ with the equation: YD2-♂ = -24.871 + 1.177X4 + 0.902X5 (R2 = 0.973). X3 and X10 mainly contributed to the body weight of D3-♀ with the equation: YD3-♀ = -22.476 + 0.432X3 + 3.153X10 (R2 = 0.976). X1 and X4 mainly contributed to the body weight of D3-♂ with the equation: YD3-♂ = -34.434 + 0.363X1 + 0.669X4 (R2 = 0.918). Comparing the pathway analysis with the gray relation analysis, we could conclude that the traits most correlated with body weight in D1-♀ were X10 and X7; in D1-♂, X6; in D2-♀, X10, X1, and X5; in D2-♂, X5; in D3-♀, X10; and in D3-♂, X4 and X1.

A new loach species of the genus Oreonectes (Teleostei, Cypriniformes, Nemacheilidae) from Guangxi, China.

A new loach species, Oreonectesandongensissp. nov. is described from the Guangxi Zhuang Autonomous Region, China. The new species can be differentiated from other members of the genus by combinations of characters: a developed posterior chamber of the swim bladder, 13-14 branched caudal-fin rays, 8-16 lateral-line pores, body width 12-15% of standard length (SL), interorbital width 42-47% of head length (HL), and caudal peduncle length 11-16% of SL. Bayesian inference phylogenetic analysis based on mitochondrial Cyt b provided strong support for validity of O.andongensissp. nov. (uncorrected p-distance 6.0-7.5%).

Integrative Taxonomy of Turcinoemacheilus Bănărescu &amp; Nalbant, 1964 in West Asia with the Description of Three New Species (Teleostei: Nemacheilidae)

Nemacheilid fishes in the genus Turcinoemacheilus are physically small members of the ichthyofauna communities of high-altitude and mountainous freshwater ecosystems. They are all distributed in Western Asia apart from a single species, described in the Himalayas. They are usually very similar in appearance, which complicates their proper identification and/or description. This is why it is important to use multidisciplinary and integrative taxonomical approaches in order to study their true diversity. In this study, three new species of Turcinoemacheilus are described from Iran, raising the total number of valid species to nine. Turcinoemacheilus ansari new species, is distinguished by the anus being situated behind the midpoint of the pelvic-fin and anal-fin origins and the short anal-fin base length. Turcinoemacheilus christofferi new species, differs by the anus being situated behind the midpoint of the pelvic-fin and anal-fin origins, with a complete lateral line reaching to the anterior part of the caudal fin. Turcinoemacheilus moghbeli new species, is distinguished by the anus being situated at or in front of the midpoint of the pelvic-fin and anal-fin origins, with a great pre-pelvic distance and a caudal peduncle length 1.5–2.3 times its length. In Western Asia, all Turcinoemacheilus species are well separated by molecular characters, showing between 3.6 and 14.1% uncorrected p genetic distances in the COI barcode region. This work shows the importance of studying the hidden diversity of under-sampled and understudied groups of organisms to have a clear image of true biodiversity in order to effectively conserve and protect it.

Morphometric and meristic traits of giant sea catfish &lt;em&gt;Arius gigas&lt;/em&gt; (boulenger 1911) from new Calabar river and Degema River, Rivers State, Nigeria

Morphometric and meristic characters of the Arius gigas species were examined from two study areas (New Calabar and Degema Rivers) for a period of six months in Rivers State, Nigeria. Total of 200 individuals, 100 from each study site, were examined and analyzed. A majority of the values for external morphometric parameters of A. gigas were higher in the New Calabar River than those from Degema River population, with no significant differences exist (p&lt;0.05) across the morphometric parameters except for pre-orbital length, post-orbital length and eye length. The meristic characters revealed variations in the mean values of dorsal fin spine (8.55±0.11 and 7.07±0.38), pectoral fin ray (5.96±0.06 and 4.23±0.26), and pelvic fin ray (14.99±1.21 and 7.51±0.52) in the study. A significant difference was noted in the number of dorsal fin spine (p&lt; 0.05) between the two populations. The mean percentage of the Length of caudal peduncle (LoCP),1st and 2nd dorsal fin (DF), length of interdorsal fin (LoIDF) and length of adipose fin (LoAF) of A. gigas in the New Calabar River were significantly higher (p&lt;0.05) than Degema River. Growth variability for standard length and all external parameters displayed allometric growth of A. gigas from Degema River. Further studies are recommended to corroborate the findings of the two populations using molecular markers for making conservation plans for exploitable A gigas species.

Morphological features and length-weight relationships of &lt;i&gt;Sarotherodon galilaeus&lt;/i&gt; from Oyan Lake, Southwestern Nigeria

Oyan Lake is one of the major sources of fish protein supply to many parts of Southwestern Nigeria. Investigation was conducted on the biometrics, length-weight relationship and condition factor of Sarotherodon galilaeus in Oyan Lake. Fish samples were obtained from fishermen using gillnets, hook and line, cast nets and traps. One hundred and thirty samples of S. galilaeus were collected for the study, comprising eighty-three (83) males and forty-seven (47) females with sex ratio of 1:0.57 (male:female). The mean total lengths for combined sexes, males and females were 15.5±0.15, 15.7±0.19 and 15.3±0.26cm while the mean total weights were 81.0±2.78, 83.8±0.56 and 75.9±4.70g, respectively. No significant difference (p&gt;0.05) was observed between mean total lengths of males and females. However, mean weight of males was significantly higher (p&lt;0.05) than females. Mean eye diameter (EYD) and length of caudal peduncle (LCP) were significantly higher (p&lt;0.05) in females. The range of number of pectoral rays (PRA) (12-14), number of pelvic rays (PVR) (4-5), number of anal spines (ANS) (2-3) and number of pelvic spines (PEVS) (1, no range) were the same in both sexes. There was strong correlation between weight/total length (r=0.93) and total length/length of dorsal fin base (r=0.72), while there was no correlation between body depth/head length. The mean condition factor (k) were 2.07±0.02 (combined sexes), 2.08±0.03 (males) and 2.03±0.03 (females). Growth was isometric for both sexes: males, 3.24 and females, 3.06. The results suggested that Oyan Lake is suitable for S. galilaeus.

Spatial Variability of Morphometric Characters of Freshwater Food Fishes from River Ganga of Districts, Kanpur, Prayagraj and Varanasi of Uttar Pradesh, India

The morphometric characters were evaluated to assess the population status of the commercial valuable food fishes collected from River Ganga at three different locations, Kanpur, Prayagraj and Varanasi. In this study, seventeen morphometric parameters were considered to examine during the month of October, 2022 to January, 2023. Usually, the various species of fishes consumed from the river Ganga. For present study, the morphometric characters like total length, fork length, standard length, pre-orbital length, post-orbital length, eye diameter, head length, pre-pectoral length, pre-dorsal length, pre-pelvic length, pre-anal length, length of dorsal fin, length of pectoral fin, length of caudal fin, length of caudal peduncle, body depth and body weight of four fish species, Labeo rohita, Rita rita, Wallago attu and Cyprinus carpio examined. A total of 25 specimens of each species were collected and the quantitative measurement of each aforesaid morphometric character provided crucial data regarding the development of fish body parts. Additionally, the positive correlations have been significantly (p &lt; 0.01 and p &lt; 0.05) detected amongst the selected morphometric characters of fishes. This study will be very crucial for fisheries management. Also, the findings will distribute the important standards for the geographical distribution of the commercially valuable food fishes. Further, the study defines that the growth of all fishes is suitable and the river Ganga ecosystem on three sites, Kanpur, Prayagraj and Varanasi is enormously favourable to the aquatic fauna especially fishes.

Morphometric Analysis of Different Parameters for Labeo boga from Head Panjnad, Alipur, Punjab, Pakistan

This study was designed to analyze the external morphometric characteristics of Labeoboga from Head Panjnad, Alipur, Punjab, Pakistan. About 48 specimens were collected and examined to address the growth patterns of the species under study for the first time, together with their morphometric characteristics for the analysis of morphological characters. The analysis of the present results for the length-weight relationship revealed that the value of regression coefficient ‘b’ was <3.0 according to the cube law, showing a negative allometric growth pattern (b = 2.710). Additionally, a highly significant positive correlation (r > 0.931; P < 0.05) was recorded for the correlation value ‘r’ among weight and length. A linear correlation was observed among 11 morphometric characters vs total length (TL), which revealed a highly significant correlation between total length vs standard length, body weight, fork length, dorsal fin length, body girth, body depth, anal fin length, and pectoral fin length, respectively. While, a moderate correlation was recorded between total length vs head length, eye diameter, and caudal peduncle length. Furthermore, the same trend was observed in the correlation significance between total body weight and other morphometric characters. The current study would be helpful for ichthyologists and zoologists in comparing different morphometric characteristics of Labeoboga.

Morphometric characters of the whitefish ludoga (coregonus lavaretus ludoga) in connection with the lake Issyk-Kul ecological and geographical conditions and its introduction

This article considers the influence of ecological and geographical conditions in the sequent whitefish ludoga (Coregonus lavaretus ludoga) relocation from Lake Ladoga to Lake Sevan and then from Lake Sevan to Lake Issyk-Kul. Morphometric studies of whitefish ludoga from Lake Issyk-Kul and a comparative analysis with similar data of this fish species of Lake Ladoga and Lake Sevan were carried out, taking into account the ecological and geographical condition of these lakes. In the course of our research, we found that the morphometric characters of whitefish ludoga during the introduction from Lake Ladoga to Lake Sevan and then to Lake Issyk-Kul changed due to the ecological and geographical conditions of these lakes. We have identified changes that occurred sequentially when moving from the plain region lake (Ladoga) to the mountain lake (Sevan) and to the mountain lake with brackish water (Issyk-Kul). These changes were mainly in the quantitative increase of some morphological parameters of these fish, such as raker counts on first branchial arch; scale counts on the lateral line; snout length and lower jaw length; predorsal distance and caudal peduncle length; head depth. In addition, there are changes characteristic of the Issyk-Kul fish, it is an increase in body depth and the dorsal fin height.

Exostoma dhritiae, a new sisorid catfish (Teleostei: Sisoridae) from the Brahmaputra River drainage, Arunachal Pradesh, India

A new species of sisorid catfish of the genusExostomais described from the Siang River in Arunachal Pradesh, northeastern India. The new species,Exostoma dhritiae, can be distinguished from congeners by the condition of the posterior extremity of the adipose-fin base, the degree of tuberculation on the dorsal surface of the head, and the shape of striae on the anterolateral surface of lips. Further, it is distinguished by the morphometric data for the body depth at the anus, maxillary barbel length, adipose fin base length, caudal peduncle length, caudal peduncle depth and the number of branched pectoral-fin rays. It is the twentieth reported species of Exostoma.

TAXONOMY AND SOME ASPECTS OF BIOLOGY OF Punitus sarana AND Punitus gonionotus

The shar punti, Puntius sarana is a small indigenous and native species of Bangladesh. In the present times because of large scale degradation of habitats and for many of the natural and anthropogenic activities the species has been reduced drastically and considered as an endangered species. On the other hand, Puntius gonionotus has been introduced in Bangladesh from Thailand and considered as an important aquaculture species. The samples of P. sarana and P. gonionotus were collected from Kumar River in Faridpur district and from local markets in Khulna city. Paired sample t-test and multiple comparisons were made for some important characteristic proportions and other biological aspects such as hepatosomatic index, dressing percentage and condition factor were calculated for both the species. Some identifying characteristic proportion were found as; head length: eye diameter = 1:3.48 (P. sarana) and 1:3.435 (P. gonionotus), standard length: head length = 1:3.94 (P. sarana) and 1:3.96 (P. gonionotus), caudal peduncle length 13.25% in case of Puntius sarana and 14.17% in case of P. gonionotus of standard length, hepatosomatic index: 0.6735 (P. sarana) and 1.114 (P. gonionotus), dressing percentage: 18.96 (P. sarana) and 21.29 (P. gonionotus) and condition factor: 1.378328 ± .23041 (P. sarana) and 1.394224 ± .13322 (P. gonionotus) were found. Significant differences were found in various morphometric proportions and meristic characteristics and in hepatosomatic index, dressing percentage and condition factor between the two species

Mask_LaC R-CNN for measuring morphological features of fish

In aquaculture management, the measurement of various morphological characteristics of fish, such as body length, body width, caudal peduncle length and width, pupil diameter and iris diameter, are the main information basis for breeders to feed, use drugs, catch, grade and make breeding characters analysis. Obtaining these information quickly and accurately can provide effective guidance for management and control in the aquaculture process, and it is conducive to improve production efficiency and increase income. By combining data expansion method and Mask_LaC R-CNN network, this paper realizes the accurate measurement of various morphological characteristics of fish, and design a non-contact measurement system of fish morphological parameters. Because the fish position and image contrast in the data set are too single, data expansion method such as shrinkage transformation, translation transformation, contrast transformation and adding noise are used to simulate a more real scene. For the loss function of Mask R-CNN, smooth L1 loss is improved by using the balanced L1 loss function; the convolution decomposition is used to realize the lightweight network structure, so that the model can accelerate the network while maintaining high accuracy. At the same time, the hole convolution can effectively improve the accuracy of the detection algorithm without additional parameters and computational cost. The enhanced data set and the Mask_LaC R-CNN experiment shows that the improved scheme improves the measurement accuracy. Under the pure background, the mIoU of 50 test images is 0.930, the relative error of body length is 1.46%, and the relative error of body width is 0.65%. Under the complex background, the mIoU of 50 test images is 0.934, the relative error of body length is 6.98%, and the relative error of body width is 8.05%.

Genome-wide characterization of three IGFs in hybrid yellow catfish (Pseudobagrus fulvidraco ♀× Pseudobagrus vachellii ♂) and the association of IGF2 allelic variants with growth traits

“Huangyou No. 1”, a new hybrid yellow catfish (Pseudobagrus fulvidraco ♀× Pseudobagrus vachellii ♂) with heterosis in growth traits, is an economically important freshwater fish in China. Among genes related to growth traits, Insulin-like growth factors (IGFs) are recognized as key factors during embryonic development and growth period. Thus, we identified and characterized IGF1, IGF2 and IGF3 gene from hybrid yellow catfish. Phylogenetic analysis showed that the IGF genes were evolutionarily-constrained and their function was conserved. Transcriptional studies indicated that three IGF mRNA expression were most abundant in liver, despite the ubiquitous expression in nine tested tissues. Further, two opposite temporal expression patterns were observed in these three IGF genes during 16 embryogenesis and larval development stages of hybrid yellow catfish, of which IGF2 and IGF3 shared the similar profile highly expressed after gastrula. Finally, single nucleotide polymorphisms (SNPs) of IGF2 were screened and genotyped in 264 hybrid yellow catfish by Sanger sequencing. Only a non-synonymous mutation (SNP 97 T > C) obeyed Hardy-Weinberg equilibrium. Association analysis indicated SNP 97 T > C significantly associated with nine growth traits (body length, full length, head length, body height, caudal peduncle height, caudal peduncle length, body width, body weight and fatness; P < 0.05). This association was also validated in a second population with 183 individuals. Overall, results from our studies highlight the importance of IGF system in mediating growth development of hybrid yellow catfish, and provide a potential marker for “Huangyou No. 1” breeding.

Sicyopterus garra Hora, 1925, a valid species of sicydiine goby from the Andaman Islands, India.

Sicyopterus garra Hora, 1925 from the insular streams of South Andaman Islands was synonymized with Sicyopterus microcephalus described from Java, South East Asia and has retained this taxonomic status since then. Recent collections of Sicyopterus from the type locality of S. garra and the examination of syntypes of this species revealed significant morphological and genetic differences from S. microcephalus and the other Sicyopterus species with papillae on upper lip. S. garra is thus a valid species and not a synonym of S. microcephalus. S. garra differs from S. microcephalus in having fewer lateral scales 53-59 vs. 57-68, fewer zigzag series (12-14 vs. 13-16), a longer caudal peduncle length (16-21 vs. 13-17), and by having a high percentage of divergence in COI gene (5.5%-5.8%).

A new species of Astronotus (Teleostei, Cichlidae) from the Orinoco River and Gulf of Paria basins, northern South America.

Based on morphological and molecular analysis of Astronotus species, a new species is described from the Orinoco River and Gulf of Paria basins in Venezuela and Colombia. Morphologically, it differs from Astronotuscrassipinnis and Astronotusocellatus in pre-orbital depth, caudal peduncle depth, head width, and caudal peduncle length, with significant differences in average percentage values. Osteologically, it differs from the two described species by lacking a hypurapophysis on the parahypural bone (hypural complex) and having two or three supraneural bones. Another characteristic that helps diagnose the new species is the morphology of the sagitta otolith, which is oval with crenulated dorsal and ventral margins and a rounded posterior edge. Genetically, the new species is distinct from all the other lineages previously proposed for the genus, delimited by five single locus species delimitation methods, and also has unique diagnostic nucleotides. Phylogenetic analyses support the monophyly of the new species as well as all other species/lineages. Astronotus species have considerable genetic, anatomical, and sagitta otolith shape differences, but have few significant traditional morphometric and meristic differences, because there is high variability in counts of spines, soft dorsal-fin rays, and lateral-line scales. It is clear that this new species is genetically and anatomically differentiated from all other species within the genus, and deserves recognition as a new valid species.

Molecular phylogenetic and morphometric analysis of population structure and demography of endangered threadfin fish Eleutheronema from Indo-Pacific waters

The threadfin Eleutheronema are the important fishery resources in Indo-Pacific regions and classified as the endangered species with considerable conservation values. Their genetic diversity and population structure remain essentially unknown but are critical for the proper management and sustainable harvests of such important fisheries. Here, the mitochondrial DNA sequences of CO1 and 16s rRNA were determined from 75 individuals of Eleutheronema tetradactylum and 89 individuals of Eleutheronema rhadinum collected from different locations of South China Sea and Thailand coastal waters. Genetic diversity analysis revealed that both E. tetradactylum (Haplotype diversity, H = 0.105–0.211; Nucleotide diversity, π = 0.00017–0.00043) and E. rhadinum (H = 0.074–0.663, π = 0.00013–0.01088) had low diversity. Population structure analysis demonstrated the shallow genetic differentiation among the South China Sea populations. The limited communication between China and Thailand populations caused the high genetic differentiation in all groups due to the low dispersal ability. Reconstruction of CO1 phylogenetic relationships and demographic studies across Indo-West-Pacific regions provided strong evidence for a shared common origin or ancestor of E. tetradactylum and E. rhadinum. Eleutheronema rhadinum were further subdivided into two distinct genetic lineages, with Clade A dominantly distributing in Thailand and Malaysia and Clade B distributing in China coastal waters. Phenotypic divergence, characterized mainly by the depth of caudal peduncle and length of caudal peduncle, was also observed for all populations, which was possibly associated with specific local adaptations to environmental changes. Our study suggested a strong need for the development of proper fishery management strategies and conservation actions for the imperiled Eleutheronema species.

Fish functional responses to local habitat variation in streams within multiple land uses areas in the Amazon

Abstract In this study, we assessed the effects of multiple land uses and local habitat variables on the composition of fish functional trophic groups (FTG’s) and on the ecomorphological traits of fish in Amazonian streams. We evaluated land use types and local habitat variables in 26 streams distributed within a land use gradient. Land use and habitat variables affected the composition of FTG’s, as evidenced by the increased abundance of diurnal channel drift feeders in areas with high dissolved oxygen and deeper thalweg. At the same time, diurnal surface pickers, as well as diggers, and ambush and stalker predators were more abundant in streams with higher canopy density. Only habitat variables affected the ecomorphological characteristics of the species. Fish with higher values of relative caudal peduncle length were positively associated with high canopy density, while fish with greater relative mouth width were negatively associated with the variables impact in the riparian zone and cover of fish shelter. The stream fish functional structure was mainly affected by the impacts caused to the local habitat resulting from different land uses. Thus, preserving forest remnants, as well as recovering degraded areas, is essential for the maintenance of aquatic biodiversity in the region.

MÔ TẢ LOÀI CÁ CHIÊN BẸT Pareuchiloglanis sp. (SILURIFORMES: SISORIDAE) Ở LƯU VỰC SÔNG ĐÀ, ĐỊA PHẬN HUYỆN PHONG THỔ, TỈNH LAI CHÂU

The genus Pareuchiloglanis (Siluriformes: Sisoridae) consists of 26 species in the world. In Vietnam, this genus has eight species, including five that are in uncertain taxonomy status. In the present study, we described one species of Pareuchiloglanis based on collections from the Da River basin in Phong Tho district, Lai Chau province. Pareuchiloglanis sp. can be distinguished from congeners by the following unique combination of characters: D. i,6; A. i,4; P1. i,14-16 (primarily i,16); C. i,6-8,6-8,i (primarily i,8,8,i); interorbital distance\eye diameter 2.4-3.4; caudal peduncle length 17.1-21.5; caudal pedunle depth 6.0-7.0% SL; length of adipose base\dorsal to adipose distance averaged 1.8; head length 19.2-24.3; anal-fin origin closer to the anus than to the caudal-fin base; adipose-fin base posterior to the tip of pelvic-fin rays; the pelvic-fin insertion located opposite to the fourth dorsal fin-ray element; maxillary barbel extending just beyond base of first pectoral-fin element; and yellow patches on dorsal surface (a broader pair on the last doral-fin ray, as large as two thirds length of pelvic-fin). Morphological analysis showed that Pareuchiloglanis sp. are closed to two species in the same surveyed area, P. tamduongensis and P. songdaensis. This paper also indicated morphological differences between Pareuchiloglanis sp. and other species that have yellow patches on dorsal surface. This species record implied the potential of biodiversity of Pareuchiloglanis in the headwaters of the Red River. These findings provide worthy data for further studies on taxonomy of this genus in northern Vietnam.

Morphometric characteristics of four important fish species from the Rwandan side of Lake Kivu

Inland fisheries are important socio-economic resources for rural communities in Africa. In Rwanda, about two million people directly depend on capture fisheries from Lake Kivu. Sustainable fisheries management requires monitoring of population dynamics that help devise effective intervention strategies. However, the relevant data such as length-length and length-weight relationships do not exist for most of the key species in Lake Kivu. The present study generated morphometric and body weight data for Limnothrissa miodon (n=82), Lamprichthys tanganicanus (n=55), Haplochromis vittatus (n=51) and Haplochromis graueri (n=34) from Lake Kivu. Length-weight relationships (W=aLb) were highly significant for all species (p &lt; 0.0001), high adjusted R2 = 78 to 98% of the variance in weight explained by total length. Negative allometric length-weight relationships were found with regression slope (b) values of 2.7 for Limnothrissa miodon, 2.8 for H. graueri, and 2.8 for L. tanganicanus, and positive (b=3.4) for Haplochromis vittatus. Length-length relationships were highly significant for all species (p ≤ 0.0001), except for the relationship between total and caudal length for L. miodon, and total and caudal peduncle length for L. tanganicanus, both not significant at p &gt; 0.05. The highest R2 was for the relationships between total and standard length for H. vittatus, and total and fork length for L. tanganicanus. No description of length-length relationships exists for these species in literature or in FishBase database. The data generated in the current study will be used to assess changes in fish populations over time.

Vanmaneniamarmorata, a new species of loach (Teleostei: Gastromyzontidae) from the middle Chang-Jiang Basin in Guizhou Province, south China.

BackgroundThe gastromyzontid genus Vanmanenia was established by Hora in 1932, based on the type species Vanmaneniastenosoma. The genus is a loach group adapted to running waters of streams from southern China, northern Vietnam and Laos. Currently, 19 valid species of the genus have been recognised. The northernmost distribution of the genus is the Yangtze River (= Chang-Jiang in Chinese) Basin and five species (V.maculata, V.intermedia, V.stenosoma, V.pseudostriata and V.gymnetrus) have been reported from the Basin.New informationVanmaneniamarmorata, a new hillstream species of loach, is here described from the middle Chang-Jiang Basin in Guizhou Province, south China. It is distinguished from its congeners by having a combination of the following characters: three triangular-shaped rostral lobules; postdorsal saddles wider than interspaces; a more backwards-placed anus (the vent to anal distance 30.5–36.9% of the pelvic to anal distance); a larger gill opening with its upper extremity reaching the level of the middle of the orbit; anal-fin base length 5.6–6.4% of SL; caudal-peduncle length 11.6–12.9% of SL; prepelvic length 51.1–53.4% of SL. Its validity is also affirmed by its distinct cyt b gene sequence divergence with all sampled congeners and its monophyly recovered in a cyt b gene-based phylogenetic analysis.