Pectoral Fin Length Research Articles

A new species of Hoplostethus from Sumatra, eastern Indian Ocean, with comments on its most similar congeners (Trachichthyiformes: Trachichthyidae).

A new species of the roughy fish genus Hoplostethus, subgenus Leiogaster, is described based on three specimens collected from Sumatra, Indonesia. This species can be distinguished from its congeners by the following characteristics: gular region covered with ctenoid scales; pelvic-fin spine smooth on its anterior edge; head depth subequal or smaller than its length (37.2%-38.6% standard length [SL], or 94.7%-99.2% head length [HL]); pectoral-fin length 35.6%-37.8% SL, reaching beyond a vertical through anal-fin origin; abdominal scutes well developed, 12-16; pectoral-fin rays uniformly black, 17-19; gill rakers on the first arch 6-7 + 1 + 13-14 = 21; pre-dorsal scales 24-27; and pyloric caeca 32. A detailed description is provided along with comparisons with its congeners. Additionally, diagnostic characters of the congeners and literature records of Hoplostethus rubellopterus and Hoplostethus melanopus are discussed.

Taxonomic characterization of five species of emperor fishes (Actinopterygii: Eupercaria: Lethrinidae) based on external morphology, morphometry, and geographic distribution in the northwestern Indian Ocean

Species of the genus Lethrinus, commonly referred to as emperor fishes, mainly distributed in the Indo–West Pacific, including the Persian Gulf and Gulf of Oman are poorly known. It is difficult to characterize them morphologically, as there are no distinguishing meristic features for the majority of species. We studied the morphological features of 65 specimens representing the genus Lethrinus to define and identify the species involved. Among the morphological characters commonly considered in this type of study, we also included new, previously undescribed characters. The results of Tukey’s post hoc HSD test for metric and meristic variables, which showed significant differences between species in ANOVA, indicate that most metric traits and the number of scale rows above the lateral line differ significantly among the five morphotypes distinguished. Principal component analysis (PCA) and discriminant function analysis (DFA) effectively showed the morphometric variation between these morphotypes. The characteristics of body depth, head length, pectoral fin length, and caudal fin length are the most distinguishing diagnostic at the species level. We determined that the collected fish specimens represented: Lethrinus borbonicus Valenciennes, 1830, Lethrinus crocineus Smith, 1959, Lethrinus lentjan (Lacepède, 1802), Lethrinus microdon Valenciennes, 1830, and Lethrinus nebulosus (Forsskål, 1775). We also confirmed their validity as distinct species. Notably, L. crocineus, previously known only from the western Indian Ocean (Africa and Socotra), is now reported for the first time from the Persian Gulf and the Gulf of Oman. Lastly, a distribution map for the Lethrinus species is included.

Allometric Growth Pattern and Hunger Tolerance of Hemibarbus maculatus Bleeker Larvae.

To clarify the allometric growth pattern and hunger tolerance of Hemibarbus maculatus Bleeker larvae, the morphological lengths of their functional organs were measured continuously and their primary feeding rates under a state of starvation were studied. A control group and starvation group were set up for this study, and 10 larvae were sampled from each group every day in order to study their allometric growth pattern and starvation tolerance. The results indicated that the Hemibarbus maculatus larvae opened their mouths for feeding at 4 days after hatching, and that the yolk sac disappeared completely at 11 days after hatching. The Hemibarbus maculatus larvae preferentially developed their heads, fins, and eyes, related to the functions of feeding, balancing, and swimming, in order to cope with complex environments. The growth inflection points for the head length, pectoral fin length, dorsal fin length, eye diameter, eye spacing, snout length, and body height were characterized by total lengths of 10.93 mm, 11.67 mm, 11.67 mm, 13.17 mm, 16.53 mm, 15.13 mm, and 15.13 mm, respectively. Prior to and following the inflection point, positive allometric growth was observed in all organs. After the inflection point, the dorsal fin continued to maintain positive allometric growth, while the others changed to isometric allometric growth. A growth inflection point was not observed for trunk length or the lengths of the tail and anal fins. The trunk length always maintained negative allometry, while the tail and anal fin lengths were reversed. The growth inflection point of the tail length was at a total length of 13.68 mm. Before and after the growth inflection point, negative and isometric allometric growths were observed, respectively. According to the relationship between the total length and number of days after hatching, the growth inflection point of the Hemibarbus maculatus larvae was concentrated at TL = 10.93-16.53 mm, which was observed 14-20 days after hatching. The point of no return for the Hemibarbus maculatus larvae was 12-13 days after hatching, and the ratio of days after hatching in the mixed trophic period to the endotrophic period was 1.75, indicating that the larvae had strong hunger tolerance. Therefore, when considering a water temperature of 22.66 ± 1.56 °C, 4-5 days after hatching is the best time to cultivate in the pond, and it should not be carried out later than 12 days after hatching.

New species of the eel genera Dysomma and Dysommina from Vietnam, South China Sea (Anguilliformes: Synaphobranchidae).

Two new cutthroat eel species are described from Vietnam. Dysomma intermedium sp. nov. has a relatively long trunk, being about half of head length and anal-fin origin more than twice pectoral-fin length behind the pectoral-fin tip; pectoral fin well developed; dorsal-fin origin over or slightly in front of base of pectoral fin; two intermaxillary teeth; four or five compound teeth on ethmovomer; single row of seven or eight teeth on lower jaw; total lateral-line pores 70-76; and 21 pre-anal and 118-124 total vertebrae. Dysommina brevis sp. nov. differs from congeners by having a trunk shorter than head length, its length 11.1%-11.8% TL; a short pre-anal length 24.6%-25.6% TL, eye diameter 11.8%-12.3% head length; three large and one or two small teeth on ethmovomer; and fewer teeth on the upper and lower jaws. In addition, a specimen representing the first record of Dysommina orientalis in Vietnamese water is documented.

Confirmation of hilsa shad (Tenualosa ilisha) in Vietnamese waters: a morphological and genetic analysis

Abstract One specimen of tropical shad was caught from the Giang Thanh River, Kien Giang province, Vietnam in a survey on 16 October 2022. We identified the specimen as the hilsa shad, Tenualosa ilisha Hamilton, 1822 using morphological analysis, and further validated by its cytochrome oxidase subunit I (COI) sequence. The specimen was 418 mm long, 1428 g in weight, with a head length of 29.0% and pectoral fin length of 31.1% of its standard length. Notably, the presence of 34 scutes, a higher gill raker count and a caudal fin length within the moderate range for Tenualosa species distinguished it from T. macrura, T. toli and T. reevesii. The COI sequence of the sample matched closely to the T. ilisha. The results confirm that T. ilisha still endures Vietnamese water, where it was thought to be extinct. Climate change and Indo-Pacific Ocean currents may introduce expansion of distribution area of the T. ilisha. Further studies on distribution of the T. ilisha and other Tenualosa species and their dynamics are needed.

Condition, Reproductive Fitness, and Fluctuating Asymmetry in Brook Stickleback: Responses to Anthropogenic Runoff

Multiple indicators have been used to assess the degree of exposure of fish to anthropogenic chemicals in their stream habitats. We hypothesized that brook stickleback (Culaea inconstans) in a headwater stream receiving urban and agricultural runoff (South Fork Whitewater River, SFWR) would exhibit poorer condition, reduced reproductive fitness, and a greater left side to right side morphological asymmetry (i.e., fluctuating asymmetry or FA) than fish from a nearby headwater stream with a forested drainage basin (Garvin Brook). Male and female fish were collected from both streams just prior to spawning in 2013–2015. In 2013 and 2014, fish were assessed for overall condition (Fulton’s K), internal measures of condition (hepatosomatic index, HSI) and reproductive fitness (gonadosomatic index [GSI], total oocyte count, and oocyte mass). In 2015, measurements of head length, jaw length, eye diameter, pectoral fin length, and pelvic fin length were made on both sides of each fish for assessing degree of FA. We observed declining condition with fish size, increased liver size, and reduced oocyte counts and oocyte size in female brook stickleback in SFWR relative to those from Garvin Brook. SFWR females had significantly higher FA than Garvin females for all structures assessed, except pelvic fin length. FA also was slightly higher for all structures in SFWR males compared to Garvin males, but differences were not significant. A composite FA index combining all measurements from an individual fish into a single value displayed highly significant differences for female fish (SFWR FA >> Garvin FA), but not for male fish (SFWR FA = Garvin FA). Exposure of brook stickleback to reduced water quality in SFWR during early development appears to increase morphological asymmetry in female (but not male) fish, and continuing exposure to compromised water quality throughout life impacts both general condition and reproductive fitness of stickleback, especially older female fish, in SFWR.

Distinguishing Hybrids of Golden Thailand and Malaysian Strains of Climbing Perch, Anabas testudineus (Bloch, 1792), Using Multivariate Analyses of Morpho-Meristic Traits

The climbing perch, Anabas testudineus (Bloch, 1792), is a commercially important freshwater fish in Southeast Asia. To meet demand, establishing stock development breeding programmes is essential. However, there is a lack of scientific literature on parent-hybrids differences. This study aims to use morphometric characteristics to identify important predictors and determine their heritability to address the knowledge gap. Two strains of A. testudineus and their corresponding hybrid groups, represented by T1–T4 (T1: golden Thai (♀) × golden Thai (♂), T2: golden Thai (♀) × Malaysian (♂), T3: Malaysian (♀) × Malaysian (♂) and T4: Malaysian (♀) × golden Thai (♂)) were used for the experiment. Thirty individuals of each strain were randomly selected from their respective tanks for morphometric characteristics assessment. Twenty-five morphometric measurements were taken, and adjustments were made for body size effects. These measurements were then subjected to multivariate analysis with a 5 % selection intensity for genetic advancement, focusing on body depth and base of anal fin length. The morphometric characters, including postorbital length, lowest body depth,the base of analfin length,total length, standard length, pre-pectoral fin length,the base of pectoralfin length, and base of pelvic fin length based on the canonical coefficient, were identified as distinguishing factors between hybrids and the parental population. The study showed that body length heritability was greater than 60 %, indicating a significant additive genetic effect that surpasses the impact of the environmental effect and thus could be used as a potential characteristic for selective breeding to improve the desired trait.

Status, distribution, and morphometric analysis of the genus Trichopodus in Sumatra, Indonesia

Trichopodus, the genus of dwarf gourami fish, is the oldest genus in the Osphronemidae family, with six valid species, three of which are found in Sumatra. In this study, the status, distribution, and morphometrics of Trichopodus leerii, T. pectoralis, and T. trichopterus from Sumatra were observed and analyzed. Although these species can be distinguished based on phenotypic characteristics, it is still possible to misidentify them in small or preserved samples. In this study, analyses were carried out on specimens in the collection of the Museum Zoologicum Bogoriense, combined with literature on the species status. The results showed that T. trichopterus and T. pectoralis were in the least concern category. T. trichopterus had the widest distribution, followed by T. pectoralis. T. leerii had the smallest distribution and is in a near-threatened conservation status. Further analysis revealed that 23 of the 25 measured morphological characteristics were informative, with the first three axes of a principal component analysis on morphometric data explaining 51.28% of the total variance in the sample. The three species were distinguished using a combination of pectoral fin length, eye diameter, pelvic fin length, and anterior snout width. Cluster analysis showed that there is consistency in the morphometrics of the species from various sample locations, where the same species are in the same clade. This research contributes to our understanding of the status and distribution of the species in genus Trichopodus and employs morphometric analysis to provide a practical key to classifying them in Sumatra.

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 < 0.01 and p < 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.

Comparative Morphological Analysis of Pellonula Leonensis Fished from Isaba Creek and New Calabar River, Niger Delta Region, Nigeria

The samall-toothed pellonula, Pellonula leonensis is ecologically and economically important. It is good source of protein to rural coastal and riverine communities because of its taste. Despite the economic significance, information on its biology are scarce. We evaluated the morphometric and meristic traits of the species from two water bodies in the Niger Delta Region. The population obtained from ISABA Creek, Delta State were significantly (P˂0.05) smaller in all the morphometric traits analysed relative to the population from New Calabar River with the exception of Pectoral Fin Length (PFL) and Pelvic Fin Length (PvFL). The range of total length, TL and weight respectively of 3.70-8.52cm (X ̅=5.14±0.034cm) and 0.20-3.40g (X ̅=0.75±0.022g) for ISABA Creek population and 6.5-9.80cm (X ̅=8.35±0.06cm) and 1.7-7.30 g (X ̅=3.84±0.083g) for New Calabar River population was observed. The range of meristic characters significantly differed between the two waters bodies (p<0.05). The observed intraspecies differences could be attributed to environmental variables, fishing pressure and genetic factors. This study reveals the need for developing conservation strategies and domestication programs for species distributed in different water system.

Minimally Invasive Collection of Biometric Data Including Maturation Stage on European Eel Using Photography

AbstractIn response to the severe decline of the European Eel Anguilla anguilla stock in recent decades, various data frameworks and research efforts toward improved management rely on the availability of site‐specific biometric data. At the same time, scientists are obligated to minimize the negative effects (stress, harm, and sacrifice) of their samplings on individuals and the population without compromising data quality. In‐field methods for biometric measurements must be quick, precise, and practical for the user. Essential information that is typically required in (large‐scale) eel monitoring programs includes body length, mass, sex, and maturation stage. As live eels are difficult to handle, individuals are typically anesthetized or killed (and sometimes stored frozen to postpone measurements) to obtain the necessary biometrics. The primary purpose of this paper was to explore the suitability of a nonlethal method based on photography for obtaining essential biometrics and maturation stage from live European Eels A. anguilla in a timely manner. In addition, we evaluated the relative accuracy of measuring the parameters that are necessary for assessing maturation stages in eels after defrosting and examined the necessity of correcting for potential shrinkage of eyes and pectoral fin. Both procedures were compared against a standard reference of measurements from freshly killed eels. We found that the minimally invasive method using alive measurements of eels' body length and mass together with digital measurements of eyes and pectoral fin from photographs had the highest agreement for maturation stage outcome with the fresh reference. Our results further reveal the necessity of correcting for shrinkage of eyes and pectoral fins (in addition to length and mass) after freezing to maximize reliability in stage classification. Consequently, we provide specialized formulae to apply shrinkage corrections for eye diameter and pectoral fin length.

Descriptions of two new species of the botiid genus Leptobotia Bleeker,1870 (Teleostei: Cypriniformes) from South China.

Two new species of Leptobotia are here described as L. rotundilobus from the Xin'an-Jiang of the upper Qiantang-Jiang basin in both Anhui and Zhejiang Provinces and the Cao'e-Jiang in Zhejiang Province, and L. paucipinna from the Qing-Jiang of the middle Chang-Jiang basin in Hubei Province, South China. Both have a plain brown body as found in L. bellacauda Bohlen & Šlechtová, 2016, L. microphthalma Fu & Ye, 1983, L. posterodorsalis Chen & Lan, 1992 and L. tientainensis (Wu, 1930). The two new species are distinct from these species in vertebral counts, further from L. posterodorsalis in vent placement and further from the other three species in pectoral-fin length. Both differ in caudal-fin coloration and shape, and dorsal-fin location and coloration, and also in internal morphology. Their validity is confirmed by their own monophyly recovered in a phylogenetic analysis based on the mitochondrial cyt b and COI genes.

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.

Allometric Growth Patterns and Ontogenetic Development during Early Larval Stages of Schizothorax waltoni Regan and Percocypris retrodorslis in Southwest China

Due to a sharp decline in resources, Schizothorax waltoni Regan and Percocypris retrodorslis have been listed as wildlife under second-class protection in China. Under culture conditions, the early development and allometric growth patterns of S. waltoni and P. retrodorslis were researched from the hatching stage to 60 DPHs (days post-hatching), and a sampling of ten to fifteen larvae was made every day, followed by measurements with Axio Vision 4.8 software (Carl Zeiss AG, Jena, Germany). Morphological indicators included the anal fin length, the body depth, the body depth at the anus level, the caudal fin length, the dorsal fin length, the eye diameter, the head length, the head depth, the pectoral fin length, the tail length, the trunk length, the snout length, the total length, and the ventral fin length. Based on the morphology development of S. waltoni Regan and P. retrodorslis, four periods of larval growth were identified: pre-flexion larvae at 0–14 DPHs and 0–16 DPHs; flexion larvae at 14–23 DPHs and 16–26 DPHs, post-flexion larvae at 23–50 DPHs and 26–52 DPHs, and the juvenile stage. In newly hatched larvae, most organs and body parts were not differentiated, and they successively developed within 26 DPHs. The depletion of the yolk sac was observed at 23 DPHs and 25 DPHs. Allometric growth mainly occurs in the head and tail regions, indicating that body parts related to feeding and swimming behaviors were more important than the other parts. In addition, the growth pattern shows that the development of organs gives priority to the functions of gill respiration, sensation, exogenous feeding, and swimming. The inflection points of body part growth patterns only appeared before 40 DAH, so future studies should concentrate focus on developing the best feeding from the first feeding to 40 DAH. These outcomes were discussed with regard to the ontogeny of the functional morphology in relation to ecology and aquaculture. It is expected that this research can provide valuable perspectives in species conservation.

Pectoral Fin Morphometry of Nile Tilapia (Oreochromis niloticus) Cultivated in Different Aerator and Filter

The anomaly of the pectoral fin is caused by an inappropriate amount of oxygen and ammonia within the water, which is expected to be resolved by the combination usage of an aerator and filter. This study aimed to analyze the combination usage of an aerator and filter with different amounts toward the growth of Nile tilapia’s pectoral fin. This study used a 2×2 factorial completely randomized design consisting of 4 treatments (ANF, AANF, AF, and AAF) with 6 replications. The measurement variable of the pectoral fin includes length, width, weight, and the ratio of the pectoral fin’s length with the total size of the fish. The measurement was analyzed using two way-ANOVA and continued with the LSD test. The results of the combination usage of the aerator and filter revealed a significant effect (P0.05) on the pectoral fin length, pectoral fin width, pectoral fin weight, and ratio of pectoral fin length to total body length. The research’s conclusion was the combination of usage aerator and filter had a positive impact on the growth of Nile tilapia’s pectoral fin. The study’s novelty is the combination usage of an aerator and filter with a different number to promote the growth of the cell within the pectoral fin of Nile tilapia. This research would benefit people through the discovery of the combination usage of an aerator and filter to improve the growth of Nile tilapia’s pectoral fin.

Evaluation of Sampling Methods for Maturation Stage Determination in the European Eel Anguilla anguilla

AbstractMonitoring data is important in ecological research, but differences between and within areas or species in data collection methods could introduce bias in the analyses. Standardizing data collection is particularly important when monitoring migratory species that have a distribution that crosses several national borders. The European Eel Anguilla anguilla is an extreme example of such a species since it constitutes one stock across the entire distribution area. One important variable collected for the European Eel is maturation stage. This data is needed to monitor silver eel escapement to assess population trends. To determine maturation, data on length, weight, diameter of the eyes, and pectoral fin length are used to calculate Pankhurst eye index and Durif's silver index. In this study, we investigated effects of precision and interobserver variability on data collection relevant for maturation stage determination according to Pankhurst and Durif's indices. We found that eye diameter differed in size between the left and right eyes; however, the mean difference (0.19 mm) is probably an artifact of the large sample size (n = 16,977) and can be regarded as being within the measurement precision. Meanwhile, there was no significant difference in pectoral fin length. These results suggest that either side of the eel could be used without losing precision. Visually determined maturation stage classifications differed from those calculated with Pankhurst and Durif's indices but could still provide useful information; hence, it is recommended to collect this variable. Measurements performed using computer software generated greater precision than using calipers, which increased interobserver variability. Since the difference was relatively small and since computer analysis of images may not always be an option, measuring method can be decided based on the level of precision needed in each case. These suggested implementations can reduce observation bias and streamline the data collection used for stock assessments of the European Eel.

Evaluation of breeding and growth performances of crossbreds and backcrossbreds with purebreds of Bangladeshi and Vietnamese climbing perch (Anabas testudineus)

AbstractThe present study aimed to improve the growth rate of the Bangladeshi native climbing perch (Anabas testudineus) through crossbreeding with Vietnam‐originated climbing perch, which is commercially cultured in Bangladesh. Therefore, crossbred between native and Vietnam strains of A. testudineus were evaluated in the first year (F1) as T1—Native ♀ × Native ♂, T2—Vietnam ♀ × Vietnam ♂, T3—Native ♀ × Vietnam ♂, and T4—Vietnam ♀ × Native ♂. In the second year (F2), backcrosses were performed between native and F1 generations as T5—Native ♀ × F1 (T3) ♂ and T6‐F1 (T3) ♀ × Native ♂ following five replicates in each treatment group. The F1 crossbreds of T4 were irregular in size with low survivability than T3, and therefore were not used as a parent in the second‐year backcross experiment. The breeding performances were reduced in the T4 (F1) and T6 (F2) compared to purebreds (T1 and T2). The specific growth rate (0.75%/day) of T5 and T6 was substantially lower than T3 and T4 but was considerably superior to the T1 and T2 purebred. The heterosis effect was highly evident in T6 (27.94%), whereas negative heterosis was determined in the crossbreds of the F1 generation (T4). Ten morphometric characteristics were compared and the caudal fin length, pectoral fin length, eye diameter, and body depth were responsible for the variation among T1–T6 groups by the second principal component. Furthermore, the results showed that the Bangladeshi native female climbing perch is linked with better breeding performances, and the Vietnam strain male is linked with better growth performance. Finally, the current breeding programme could enhance native climbing perch growth and survivability, which may have aquaculture potential and can be used through careful artificial selection on the commercial farm.

A new cryptic species of the pineapple fish genus Monocentris (Family Monocentridae) from the western Pacific Ocean, with redescription of M. japonica (Houttuyn, 1782)

A new pineapple fish is described based on 26 type and 80 non-type specimens collected from Taiwan, Vanuatu, the Solomon Islands, and Queensland, Australia. This new species is sympatric with and similar to Monocentris japonica but can be distinguished from the latter in having only 6 or 7 scales on the third scale row below the lateral line; excisura notched and a small pseudo-excisura present on the sagittal otolith; consistently greater head depth, body depth, postorbital length, dorsal-fin-pelvic-fin length, and dorsal-fin-pectoral-fin length in proportion to standard length. A detailed description and designation of neotype are provided for M. japonica. DNA barcoding analysis supports the distinction of the new species with an estimated average COI gene divergence of 3.6 % from M. japonica.

Comparing morphological, parasitological, and genetic traits of an invasive minnow between intermittent and perennial stream reaches

Abstract Invasive fishes are a major environmental issue at the global scale, particularly for their impacts on freshwater ecosystems via the mechanisms of hybridisation, competition, predation, and disease transmission. This is of special conservation concern on the Iberian Peninsula due to the high level of endemism. With the aim to improve our knowledge on the invasion process of non‐native fishes, the present study consists of analysing key biological traits potentially related to their colonisation capacity: morphology, parasite communities, and genetic diversity. A non‐native population of Languedoc minnow Phoxinus septimaniae (leuciscid species native to south‐east France) was assessed in Tordera Stream (north‐eastern Iberian Peninsula). Fish were sampled in mid‐May (reproductive period) 2018 and 2019. Biological traits were compared between colonising and resident individuals from stream reaches of intermittent and perennial flow, respectively. After adjusting for fish size/body mass with analysis of covariance, body condition and health status (external and internal examination) tended to be better in the intermittent reach. Parasite load (number) and diversity (Shannon index) were significantly higher in the perennial reach. Fish development was also more stable in colonising minnow, as detected by low levels of fluctuating asymmetry for the eye diameter and the length of pectoral fins (adjusted for bilateral character size). Genetic diversity (microsatellite markers) was lower in resident minnow. Minnow genetic homozygosity (index of internal relatedness) was positively associated with parasite load and developmental instability (high fluctuating asymmetry levels). Our results show that colonising minnows display particular profiles of morphological, parasitological, and genetic traits that apparently allow these individuals to increase their dispersal capacity to survive and reproduce in harsher environmental conditions. The potential mechanisms may be related to a wider physiological tolerance, better immune response, parasite resistance/tolerance, and genetic diversity in colonising specimens. Such information reveals the specific traits of successful fish invaders under a seasonal colonisation dynamic. These data are relevant for environmental managers, to predict and identify areas vulnerable to invasion, in order to establish monitoring programmes for early detection, which will help to reduce the spread of non‐native fish populations.

Length-Weight Relationships and Other Morphological Traits of Fishes in the Mangrove of Hainan, China

The length–weight relationships (LWR) and other morphological traits for 6417 specimens in 74 fish species collected seasonally, from July 2020 to April 2021, in the mangrove of Dongzhaigang Bay, Hainan Province, China, are presented. This involved, for all species, a sample size, and minimum and maximum lengths; in addition, for most species, it involved linear relationships between the standard length and body height and width, the height of the caudal peduncle, the pectoral fin length, and the eye diameter. This extensive coverage of mangrove-resident fish species (as opposed to species using the mangrove only as a nursery) is a first for Hainan. The various morphological traits of the mangrove fish are, for several species, the first to be published since these species’ original descriptions.