Positive Allometric Growth Research Articles

Length-Weight Relationship and Condition Factor of Labeo rohita (Hamilton, 1822) in Aquaponics System

The present experiment was conducted in circular FRP tanks kept indoor under polycarbonate house to provides information on the length-weight relationship and condition factors of Labeo rohita in aquaponics system. Aquaponics, an integrated system of aquaculture and hydroponics, has gained significant attention due to its sustainable and efficient nature. Understanding the growth dynamics and condition of fish within such systems is crucial for optimizing production and maintaining fish health. The length weight relationship were estimated by linear regression equation. The species exhibits positive allometric growth (b>3) with the values of condition factor (K) being greater than one, indicating the well-being of the species in its natural habitat. The water quality parameters were within the acceptable range for fish production. A fine mesh net is used to scoop fishes. The fish total length was measured from the anterior tip of the snout to the distal end of the caudal fin, and its weight was assessed using a precision single-pan electronic balance. Result shown that, the length-weight relationship of 900 experimental fish in aquaponics system with different stocking density shows that the treatment T2 performed better than T1 and T3. L. rohita juveniles reared in experimental tanks exhibited positive allometric growth and in good condition of health. This growth pattern favours fish farming as it enhances its profitability. The values of ‘K’ ranged from 0.97-1.00 which depicted good condition of fish in these water bodies. These observed parameters were useful to evaluate the well-being of L. rohita population in the aquaponics system and provided useful information on fish biology for scientific management of fisheries.

Metabolic and morphometric analysis of allometric and total liver growth in Post-Hatch chickens

Introduction: This study examines metabolic and morphometric changes in chicken liver metabolism during the post-hatch growth period (days 4–20). During this period, liver metabolism transitions from using yolk-derived lipids to feed derived carbohydrates and proteins. The period also encompasses distinct growth phases with implications for metabolic impacts on total and allometric (proportional) growth.ObjectivesIdentify shifts in metabolites and pathways that occur during the change in nutrients and relate these to patterns of total and allometric liver growth.MethodsLiver samples were collected every other day between days 4–20 and analyzed using metabolomic and morphometric approaches to relate metabolic changes to growth. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to identify trends in the data. Cross-validation ANOVA, and network analyses were applied to evaluate metabolic changes across the time periods.ResultsThree liver growth periods were defined. Period A (days 4–8) exploited stored nutrients to support rapid growth. Period B (days 10–14) was transitional as stored nutrients were depleted and feed became the major metabolic driver. By period C (days 16–20) the liver is fully dependent on feed. Positive allometric growth occurs predominantly during period A while the organ continues to grow throughout the entire time.ConclusionsMetabolic pathways exhibit distinct networks as nutrient resources change over the early post-hatch period. These findings provide a framework for understanding how nutrient-driven metabolism influences liver scaling and functional maturation.

Some biological aspects of Penaeus semisulcatus (Decapoda, Penaeidae) in the Iraqi marine waters

The study explored the fishery, growth, and reproductive biology of the green tiger shrimp, Penaeus semisulcatus, in Iraqi marine waters of the northwest Arabian Gulf from November 2022 to October 2023. Monthly shrimp landings varied significantly, ranging from a low of 57 tons in December 2022 to a high of 407 tons in September 2023, totaling 3,515 tons over the entire year. During this period, 2,394 specimens of P. semisulcatus were sampled, measuring between 10.0 and 25.0 cm in length. The length-weight relationship revealed that male P. semisulcatus exhibited isometric growth, while females showed positive allometric growth. The average condition factor for males was 1.01 ± 0.061, while females had an average of 1.03 ± 0.090, indicating good health for both sexes. The species' growth model was represented by the formula Lt= 28.7 (1-exp(-0.45(t+0.326))). The overall sex ratio was found to be 1:1.06 (male to female). The length at which 50% of the population reaches maturity (Lm50) was determined to be 8.4 cm. The gonado-somatic index (GSI) values for females varied from 2.11% in October to 8.95% in March. These results can contribute to providing information for species management in the study region.

Acoustic target strength measurement of striped goatfish (Upeneus vittatus)

The Striped Goatfish (Upeneus vittatus) is a demersal species of significant ecological and economic value, particularly for small-scale fisheries in Aceh Province. Accurate biomass estimation and species identification in hydroacoustic surveys rely heavily on precise target strength (TS) reference values. This study aimed to establish reference TS values for U. vittatus by examining the relationship between TS and fish morphology. Specimens collected from northern Aceh waters were measured for total length (TL: 17.3–28.3 cm) and weight (W, g). TS measurements were conducted using a single-beam echosounder (Simrad EK15) operating at 200 kHz with a pulse duration of 0.16 ms in a controlled water-tank environment. This approach enabled the assessment of TS variability across specimens with different TLs. A robust relationship between TL and weight revealed positive allometric growth (b = 3.2932, R² = 0.94) in the study. Furthermore, TS analysis demonstrated a logarithmic increase with TL (R² = 0.6459), in alignment with theoretical predictions. These findings contribute to more accurate biomass estimation and support sustainable management strategies for U. vittatus populations in northern Aceh, Indonesia. Future research should encompass a broader range of fish sizes and incorporate additional biological variables to refine TS prediction models further.Keywords:GoatfishAcehLWRTSMullidae

Evaluation of Biometric and Breeding Biology of the Striped Snakehead Channa striata in the Haor Region: Conservation and Effective Management

AbstractThis study was investigated to assess growth patterns, sex ratio, first sexual maturity, gonadosomatic index (GSI), fecundity and ovarian development of Channa striata in the Haor of Kishoreganj, Bangladesh, for long‐term management and conservation purposes. The results of the study indicated that the female fish showed positive allometric growth (b > 3), whereas the male showed negative allometric growth (b < 3). There were no significant differences (p > 0.05) in the Fulton's condition factor (CF) and relative condition factor (Kn) between the sexes. The Kn value indicates that the fish is in excellent health condition. The chi‐square test indicated a slight deviation from a 1:1 sex ratio for the sampled months, with a statistically significant difference (χ2 = 0.04, p < 0.05). The findings indicated that 50% of female and male fish reached sexual maturity at lengths of 29.30 and 26.74 cm, respectively. The results showed that both sexes reached their maximum GSI value in June, whereas October recorded the lowest value. The findings showed that the mean absolute fecundity was 12,049 during the study period, with June showing the peak value (28,768) and December showing the lowest value (3128). The microscopic study of gonadal tissues identified five separate stages of gonadal development. This study will contribute to comprehending the reproductive traits of C. striata and further contribute to sustainable fisheries management in the Haor region.

Asymmetrical chela growth patterns and correlation of chela shape to inhabited gastropod shells in Pagurus bernhardus (Linnaeus, 1758) (Decapoda, Anomura, Paguridae)

We investigated the growth patterns and morphological changes in the chelae of the heterochelate hermit crab Pagurus bernhardus using µCT and SPHARM analysis, correlating our findings with three different types of shells offered for protection. In males, the right chela exhibited positive allometric growth compared to the left, leading to significant size differences, whereas females showed isometric growth. This sexually dimorphic growth pattern suggests sexual selection for chela display and agonistic behavior in males. Significant length-specific growth differences were found between the chelae. The left chela exhibited positive allometric growth in the chela finger (pollex) compared to the manus, while the right chela showed isometric growth. If the left chela represents the derived state, genetic factors predominantly influence its growth and shape for biological roles such as food manipulation and grooming. Conversely, if the right chela is the derived state, it may indicate an adaptation for better shell closure in gastropod shells. There was no sexual dimorphism in the length-specific growth pattern and shape changes during ontogenesis. Shape analyses revealed significant changes in chelae morphology during ontogenesis, with correlations to the inhabited shells. These changes were particularly pronounced in the right chela, used for closing the shell aperture. Shape analysis of non-allometric data showed no significant differences between shell groups, indicating that shape changes are primarily due to allometric growth. Phenotypic plasticity may also play a role. Sexual dimorphism was significant in the shape of both chelae and was also evident in non-allometric data, suggesting shape dependence.

Morphometric and Reproductive Trends Reveal Near-Equal Sex Ratio, Positive Allometric Growth, and Early Maturity of Euthynnus affinis in Southern Philippine Waters

Ichthyometric indices and gonadosomatic dynamics provide essential insights for fisheries management and policy development, emphasizing their role in sustainable resource utilization. Our study presents updated information on the sex ratio, length-weight relationship, and length at first maturity of Euthynnus affinis in Southern Philippine waters: Celebes Sea, Moro Gulf, Sarangani Bay, and Davao Gulf. A total of 1,314 Euthynnus affinis specimens ranging from 14.00 cm to 64.70 cm collected using handline, purse seine, and ring net, were analyzed from multiple fishing ports across these four study sites. We sampled the E. affinis population which exhibited a near-proportional distribution of sexes, with an overall ratio of 1:0.59. A higher prevalence of males was observed, with a calculated male-to-female ratio of 1:0.59 (p-value < 0.05, χ² = 4.36), indicating a significant deviation from an expected 1:1 ratio. The relationship between fork length (FL, cm) and weight (W, g) was expressed as W = 0.0104 FL3.1483 for males and W = 0.0137 FL3.0639 for females. The length-weight analysis revealed a positive allometric growth pattern, indicating that E. affinis becomes rotund deeper-bodied as it increases in length. The correlation coefficients (R²) were high, at 0.9760 for males and 0.9577 for females, confirming a strong relationship between length and weight. The b-values exceeding 3 further support a positive allometric growth pattern, suggesting that the species grows proportionally more in weight than in length. The length at 50% sexual maturity (Lm50) was estimated at 37.18 cm, while 95% of the population (Lm95) reached maturity at 45.36 cm. For females, Lm50 and Lm95 were 35.19 cm and 41.48 cm, respectively, whereas males reached maturity at 38.43 cm (Lm50) and 49.90 cm (Lm95). We present these findings that highlight early sexual maturation in E. affinis, underscoring the need for targeted management strategies to ensure the sustainability of its populations. Our paper reveals the near-equal sex ratio, positive allometric growth, and early maturity of Euthynnus affinis, highlighting the need for science-based fisheries management to sustain population stability. We propose establishing minimum catch size limits above 37.18 cm (Lm50) to allow individuals to reach reproductive maturity and above 45.36 cm (Lm95) to ensure that most individuals have spawned at least once before harvest. Additional measures, including protecting spawning stocks, implementing seasonal fishing closures, and continuously monitoring population trends, can help prevent overfishing and ensure long-term resource availability. Thus, localized management strategies and adaptive policies are essential to account for environmental changes and optimize economic benefits for fishers.

First documentation of population dynamics and reproductive biology of big-scale sand smelt, A. boyeri Risso, 1810 in the coastal waters of the Southeast Caspian Sea- Northern Iran

IntroductionTo effectively manage fish stocks, evaluating various aspects of population dynamics is considered crucial. Understanding invasive species is essential for conservation efforts. This study represents the first documentation of population parameters.MethodsFor this purpose, the population dynamics parameters, including growth, mortality, and recruitment of A. boyeri, found in the Coastal Waters of the southeast Caspian Sea of Northern Iran, were analyzed using FiSAT II software. ResultThe analyzed specimens were sampled with a total weight range of 1.2 to 12.51 g and a total length range of 60 to 125 mm. The population has a 5-year life cycle. The length-weight relationship was estimated as W=0.0055 L3.0774 for males and W= 0.0083 L2.9185 for females. The slope value (b) of the length-weight relationships obtained for A. boyeri were between 2.69-3.13 with an average value of 2.91. While populations of A. boyeri showed negative allometric growth patterns, the males of exhibited positive allometric growth patterns, whereas the females had negative allometric growth patterns. The von Bertalanffy growth function fitted to back-calculated size at age data was: Lt = 126.5 [1- exp - 0.34(t + 0.234)] and Lt =131.3[1-exp- 0.35(t + 0.374)] for males and females respectively. The average relative condition factor was reported to be 0.62 and 0.79 for males and females respectively. The growth performance index (∅’) was reported to be 1.74 and 2.10 for males and females respectively. The total mortality of 1.73 year–1, consisting of natural mortality of 1.38 year–1 and fishing mortality of 0.35 year–1 and 1.21 year–1, consisting of natural mortality of 0.90 year–1 and fishing mortality of 0.31 year–1 was reported for males and females respectively. An exploitation rate of 0.20 and 0.26 for males and females respectively, is suggestive of a less exploited state of the fish. For both sexes, the length at first maturity was found to be higher than the length at first capture, a condition that can disturb the stock, as such the utility of a net with a relatively larger mesh size is advisable. The sex ratio was 1:1.34 in favor of females. For both sexes, the reproductive season, evaluated from GSI, extended from March to June, with a peak in April. The average absolute and relative fecundities were 2865 eggs and 684 eggs g-1 of body weight respectively. The diameter of oocytes ranged from 0.028 to 0.25 mm with a mean value of 0.54. DiscussionThe life-history patterns of A. boyeri in the population under study imply that the population of this species in the southeast Caspian Sea differs markedly from those of other localities of its range distribution. The differences were thought to be due to differences in geographical locations. The current research on the population dynamics of A. boyeri can be used as the baseline data for its management stocks.

Seasonal Shifts of Morphological Traits and Dietary of Mactra veneriformis (Bivalvia: Mactridae) Populations in the Northern Yellow River Delta's Intertidal Zone.

In order to examine the seasonal variations in the morphological characteristics and diet of Mactra veneriformis in the Northern Yellow River Delta's intertidal zone and provide a scientific basis for its resource conservation and population restoration, tested clams were collected in four consecutive seasons from summer of 2022 to spring of 2023. Morphological traits were measured, and the DNA of the stomach contents was analyzed using high-throughput sequencing. The tidal differences and seasonal variations in the northern habitat of the Yellow River Estuary significantly affect the morphological characteristics and growth of M. veneriformis. Among the four seasons, significant differences in the morphological characteristics of M. veneriformis were observed between the middle-tide and low-tide zones (p < 0.05). In both middle-tide and low-tide zones, the morphological characteristics and body wet weight of M. veneriformis in winter were significantly higher than those in other seasons (p < 0.05). Moreover, the morphological characteristics of M. veneriformis were extremely significantly influenced by the interaction between tide and season (two-way interaction, p < 0.001). In all seasons, M. veneriformis in the middle- and low-tide zones exhibited positive allometric growth. While there was no significant difference in the stomach content between the spring and summer samples in the same tidal zone (p > 0.05), there was a significant difference between the middle- and low-tide samples in winter (p < 0.05). This suggests that seasonal variations, rather than tidal differences, had a larger impact on the diet of M. veneriformis in the northern Yellow River estuary and that feeding differences may be related to changes in environmental factors, such as temperature. The findings of this study provide initial insights into the feeding ecology of M. veneriformis and offer a scientific foundation for the conservation and management of its resources.

Postnatal development in a specialized bird: Quantitative and qualitative analysis of pelvic girdle morphological changes in Rhea americana (Aves, Palaeognathae).

The greater rhea (Rhea americana) is the largest bird in South America. It is flightless and cursorial, with a precocial postnatal development. This study aims to describe the postnatal morphological changes in the pelvic girdle of Rhea americana, focusing on ontogenetic scaling and gross anatomy to provide insight into the potential relationship between structure and function in cursorial birds. The pelves of 18 specimens representing four postnatal stages, were studied. Gross anatomical observations and staining methods were used to identify bone and cartilage, providing detailed information about qualitative morphological changes. Quantitative changes were assessed through linear regression analysis using pelvic linear dimensions and body mass to determine allometric growth patterns. The pelvic girdles of immature specimens are characterized by unfused bones, including the vertebrae synsacrales and the medial borders of the ilia, and small cartilaginous areas at the caudal end of the ilium, ischium, pubis, antitrochanter and tuberculum preacetabulare. These immature traits persisted until the most advanced juvenile stages were studied, indicating the slow postnatal growth typical of precocial birds. Similar to other precocial birds, the greater rhea exhibits large bone areas in its pelvic girdle, providing the mechanical strength necessary for locomotion from hatching. The pelvic dimensions showed a combined pattern of allometric and isometric growth related to hindlimb function and body support. The positive allometric growth of the ilium contributed to its increasing verticalization and narrowing, providing an increased dorsoventral surface area for the attachment of the powerful proximal hindlimb muscles. In contrast, the isometric growth of the intertrochanteric width helps in the uniform distribution of loading caused by body mass, providing adequate stability and support.

Occurement assessment of helminth parasites in Euthynnus affinis from Banten, Indonesia

Abstract. Indaryanto FR, Kamal MK, Butet NA, Affandi R, Tiuria R. 2024. Occurement assessment of helminth parasites in Euthynnus affinis from Banten, Indonesia. Biodiversitas 25: 4978-4985. As an economically valuable fish, Euthynnus affinis requires regular surveillance and assessment of the prevalence of helminth parasitic infestation in Banten waters, Indonesia. In the districts of Cituis-Tangerang (North Banten), Labuan-Pandeglang (West Banten), and Binuangeun-Lebak (South Banten) in the waters of Banten, E. affinis were collected in November 2023 to January 2024. Seven species of helminth parasitic were identified to infect E. affinis in Banten: Anisakis typica (intensity 1.17; prevalence 14.65%), Tentacularia sp. (intensity 1; prevalence 0.64%), Dinurus sp. (intensity 17.75; prevalence 7.64%), Didymozoid sp. (intensity 2.25; Prevalence 7.64%), Rhadinorhynchus sp. (intensity 24.86; prevalence 87.90%), and Acanthocephalus sp. (intensity 24.86; prevalence 87.90%) are the seven species of helminth parasitic that infect E. affinis in Banten. The overall prevalence of helminth parasitic infection was categorized as moderately prevalence (89.17%) with a moderate intensity (27.32). Despite severe infestations of distinct helminth parasitic species, the mean condition factor (K) values for parasitized and non-parasitized fish did not differ appreciably. Positive allometric growth was observed in both parasitized and non-parasitic fish. Helminth parasitic infection exceeding 80 individuals/fish significantly affects the Gonado Somatic Index (GSI). Fish measuring 25-30 cm in total length were found to be susceptible to helminth parasitic infection; however, there was no correlation between fish length and parasite abundance (r2 = 0.0223). Males had a higher infection rate compared to female fish. There was no statistically significant difference in the abundance of parasites across the three locations. The host's diet was found to affect the parasitic infection. The greatest diversity of parasite species was discovered in Labuan, West Banten.

Population dynamics and seasonal variation in biological characteristics of black sea bream (Acanthopagrus schlegelii) in Zhanjiang coastal waters, China

This study examined the population dynamics and seasonal variation (winter-summer) in the biological characteristics of black sea bream (Acanthopagrus schlegelii) in Zhanjiang coastal waters, China. Key growth parameters were estimated using the von Bertalanffy growth model, revealing an asymptotic length (L∞) of 505.05 mm and a growth coefficient (K) of 0.26 year-¹, with an estimated longevity of 11.24 years. Mortality analysis showed a total mortality rate (Z) of 0.35 year-¹, primarily driven by natural causes (M = 0.33 year-¹) with minimal fishing impact (F = 0.02 year-¹), resulting in a low exploitation rate (E) of 0.05. Length-weight relationship (LWR) analysis indicated positive allometric growth in females and nearly isometric growth in males, with significant seasonal variations in condition factors (K). Yield Per Recruit (YPR) analysis identified a maximum sustainable exploitation rate (Emax) of 0.421, with a conservative management approach suggested at E0.1 = 0.355. Seasonal variations in reproductive indices, with higher Gonadosomatic Index (GSI) and Hepatosomatic Index (HSI) in winter, highlight the species’ reproductive cycle. The findings suggest that Acanthopagrus schlegelii is stable, with low fishing pressure. Seasonal GSI and HSI variations suggest fisheries management should time fishing to reduce impacts on reproductive success. Maintaining exploitation rates below Emax is essential for sustainable management, contributing valuable insights for fisheries conservation in coastal China.

Length‐Weight and Length‐Length Relationships of Three Small Indigenous Ornamental Fishes Collected From Jorasar River of Sonitpur District, Assam, India

ABSTRACTThe present study describes the length‐weight relationships (LWRs) and length‐length relationships (LLRs) for three species: Parambassis baculis (Hamilton 1822), Gagata cenia (Hamilton 1822) and Mystus tengara (Hamilton 1822) from the Jorasar river in Sonitpur district of Assam, India. The study shows positive allometric growth (3.133) for M. tengara, isometric growth (2.916) for G. cenia, and negative allometric growth (2.295) for P. baculis, with regression coefficients (r2) 0.953, 0.969, and 0.955, respectively. The Parameter a was recorded as 0.007 for M. tengara, 0.013 for G. cenia, and 0.030 for P. baculis. The current study will contribute to the conservation of these ichthyofaunas while enhancing fish stock analysis for appropriate management.

Biology of One of the Most Abundant Mesopelagic Fish in Icelandic and Surrounding Waters: The Krøyer's Lantern Fish Notoscopelus kroyeri (Malm, 1861)

ABSTRACTMyctophids play an essential role in the marine ecosystem, linking the surface to the mesopelagic layer through diel vertical migration, and contributing to carbon sequestration. However, basic knowledge of their biology and distribution is still limited. Here, we described the length and age distribution, growth and otolith morphometrics for one of the most abundant myctophid fish of the Northeast Atlantic, the Krøyer's lantern fish Notoscopelus kroyeri (Malm, 1861). Individuals were sampled opportunistically by pelagic trawls during the International Ecosystem Summer Survey in the Nordic Seas (IESSNS) conducted in July 2020 and 2021. We provide the length–weight and otolith–fish size relationships and the size distribution for 336 N. kroyeri individuals collected along Iceland's south and west shelf, the Iceland Basin, and the Irminger Sea. Fish were primarily distributed along the Reykjanes Ridge and the continental shelf at depths between 0 and 550 m. Three size groups, corresponding to three different age groups, with individuals from 2 to 9 years old, were detected across sampling areas. We found positive allometric growth during both sampling years. Linear regressions were significant between otolith length, width and area, and fish length and weight, with adjusted r2 values ranging between 0.93 and 0.94. This study provides new information on the biology and distribution of one of the most abundant mesopelagic species in south Icelandic and surrounding waters.

Growth, mortality and stock assessment of &lt;i&gt;Metapenaeus affinis&lt;/i&gt; (Decapoda, Penaeidae) from Iraqi waters

Jinga shrimp (Metapenaeus affinis) is one of the most productive shrimp fisheries in Iraqi waters. The study aimed to evaluate the growth, mortality, recruitment, yield-per-recruit, and virtual population analysis (VPA) of the M. affinis shrimp in these Iraqi waters. Samples were collected from the nursery grounds of the species in east Hammar marsh and the fishing grounds in Iraqi marine waters between November 2022 to October 2023. A total of 8021 M. affinis ranged from 2.0 to 15.6 cm TL (0.6-6.0 cm CL) were examined. The length-weight relationship exhibited a positive allometric growth pattern. Total length-frequency data for combined sexes was analyzed using the FiSAT II software. The asymptotic length, growth coefficient and growth performance index were 16.3 cm, 0.92 and 2.388, respectively. Total, natural and fishing mortalities were 3.69, 1.82 and 1.87, respectively. The current exploitation rate (Ecur) was 0.51. Length at first capture (Lc50) was higher than at first maturity length (Lm50). Recruitment continued throughout the year, with one major peak in April. The analysis of relative yield per recruit and relative biomass per recruit indicated that the Ecur of the stock was equal to its optimal level (E0.1= 0.520) and below its maximum sustainable yield (Emax= 0.628). To effectively manage the M. affinis stock, it is essential to adjust the mesh size so that the total length of the species at first capture must not be less than the length at first maturity. Consequently, it may have a chance to breed, and the nursery grounds should be protected from illegal fishing.

Length-weight&amp;nbsp; relationship, condition factor, morphometric and meristic characteristics of &lt;em style="mso-bidi-font-style: normal;"&gt;Ctenopoma kingsleyae&lt;/em&gt; from Esa-Odo Reservoir, Nigeria.

Anabantid, Ctenopoma kingsleyae is a commercially important fish being captured as a food and aquarium fish. Limited literature is available on the biology of the fish. Therefore, this study investigated the length-weight relationship, condition factor, morphometric and meristic characteristics of C. kingsleyae from Esa-Odo water Reservoir, Nigeria. Fish collected (n = 90) from fishermen were subjected to morphometric measurements to the nearest length (0.1cm) and weight (0.1g) and meristic counts were recorded in the laboratory. Results revealed the fin formula of C. kingsleyae was D1xvii, D2 9-11, A1 ix, A2 10-11, P 11-13, vi/5, TLr 25-27. The b value for males, females and combined sexes were 10.014, 12.7 and 12.81 respectively, indicating positive allometric growth for all the samples. The mean condition factors, 1.95±0.02, 2.03±0.02 and 2.00±0.01 were recorded for males, females and combined sexes respectively, implying that the fish are in good health condition. The correlation coefficient (R) of 0.8925, 0.9175 and 0.9507 were recorded for males, females and combined sexes respectively, revealing a positive relationship between the weight and total length of the fish. Positive correlations were observed between the total length and each of the other morphological characteristics of the fish (p ≤ 0.05). Data generated from this study can form baseline information for the conservation, production and management of C. kingsleyae reservoirs in Nigeria.

Morphological and ecological approaches in reproduction of the endemic catfish of the eastern Amazon.

This study aimed to describe reproductive ecology based on morphological aspects of Peckoltia oligospila in stream rapids, eastern Amazon. A total of 186 fish (75 males and 111 females) were collected. The sex and gonadal maturity stage of these specimens were obtained based on histological characteristics of the gonads. The sex ratio, gonado-somatic index (GSI), relative frequency of the different maturity stages, size at first sexual maturation, condition factor of the population, and fluviometry were evaluated during the study. There was a significant female frequency during the study. The population exhibited positive allometric growth without differences between sexes. GSI and relative frequency showing a reproductive period synchronized in February, and the species exhibited parcelated spawning. L50 was estimated at 5.85 and 7.39 cm for females and males, respectively. There were significant differences in the condition factor only in females that showed a highest value in August. Thus, based on the results P. oligospila has an intermediate strategy between the opportunistic and equilibrium strategies.

From hatching to juvenile: Larval development of Vieja fenestrata (Teleostei: Cichlidae).

This study delves into the early development of Vieja fenestrata (Cichlidae), with a specific focus on the description of external morphological and morphometric changes, and growth patterns from hatching to the loss of larval characters under controlled laboratory conditions at a temperature of 28°C. Asynchronous hatching was observed between 58 and 60 h postfertilization, with the posterior body emerging first. Over 14 days, significant morphological, physiological, and behavioral changes were observed, revealing a complex developmental trajectory. The initial developmental phases were characterized by rapid vascularization, fin differentiation, and heightened activity, and the subsequent days witnessed the flexion of the notochord, emergence of swim bladder functionality, and transition to exogenous feeding. Maturation progressed with the absorption of the yolk sac, regression of cement glands, and fin ray development, culminating in metamorphosis by 14 days post-hatching. Throughout this period, evolving pigmentation patterns and structural adaptations highlight the species' adaptive strategies. During the larval period of V. fenestrata, substantial changes in morphological proportions were observed. Before the inflection, tail length, trunk length, and body depth had negative allometric growth, and head length, eye diameter, and snout length had positive allometric growth. After the inflection, body depth and snout length showed positive allometric growth; head length and trunk length exhibited isometric growth, whereas tail length and eye diameter demonstrated negative allometric growth. These findings contribute insights into the intricate developmental dynamics of V. fenestrata. Moreover, further research may explore these developmental dynamics' ecological and evolutionary implications.

Assessment of River Ecological Health Status and Interbasin Water Transfer Potential: Case study of Luapula River Basin in Zambia

Assessment of River Ecological Health Status and Interbasin Water Transfer Potential: Case study of Luapula River Basin in Zambia

Length-weight relationships and condition factors of 24 mesopelagic fishes from the South China Sea

Length-weight relationships and condition factors of 24 mesopelagic fishes from the South China Sea