Morphometric and meristic variations between non-reproductive and reproductive kutum females (Rutilus frisii kutum,Kamensky, 1901), in the southwest Caspian Sea

Intraspecific phenotypic differences in climbing perch Anabas testudineus (Bloch, 1792) populations may be linked to habitat adaptations

The climbing perch, Anabas testudineus, is a nutritionally and economically significant food fish. The present study reveals the first comprehensive description of the life-history traits of A. testudineus scooped up through different traditional fishing gears from July 2020 to December 2020. Among the 120 collected specimens, the smallest and largest specimens were 8.5 cm-14.6 cm TL in Nilphamari and Patuakhali, respectively. The estimated b values for LLRs indicated positive allometric growth in all sampling points (b > 1.0). The LWRs of A. testudineus indicated positive allometric growth in the Gazipur and Nilphamari districts (b > 3.00) and negative allometric growth in the Patuakhali and Khulna districts (b < 3.00). A Wilcoxon sign-ranked test for WR showed no significant dissimilarity from 100, signifying the balanced habitat for A. testudineus. The estimated a3.0 was minimum in Khulna (0.0110) and maximum in Nilphamari (0.0825). "The Lm was estimated at 7.4032 (7.4) cm TL in Nilphamari and 8.86 (8.9) cm TL in Patuakhali". Nineteen of twenty morphometric measurements and ten of twelve meristic characters showed substantial variations (p < 0.0001). The principal component analysis indicated shape variation and explained 85.361% of the total variance and showed differences in TL, SL, HL, LBD, LE1, D1D2, A1A2, and VV2. The cluster heatmap demonstrates that the other stocks segregated Gazipur stock. Our findings reveal a significant dataset about intraspecific phenotypic differentiation, which will aid the long-term exploration and management of A. testudineus species in Bangladesh and its neighboring countries.

Biometric indices, growth pattern, and physiological status of captive-reared indigenous Yellowtail brood catfish, Pangasius pangasius (Hamilton, 1822)

The current study was conducted to comprehend the variation of the growth pattern and the physiological status of Pangasius pangasius (Hamilton, 1822) reared in the pond from July 2021 to September 2021. A total of 90 brood individuals were collected from the Meghna River and studied for the present experiment. The overall growth pattern for P. pangasius was isometric (b = 3.00) in the Meghna River, while the male fish showed positive (b > 3.00) and the female showed a negative allometric growth pattern (b < 3.00). The Fulton's condition factor (KF) value was greater than 1, indicating a healthy population and a habitat with abundant food sources. Moreover, the KF value was found to be substantially related to total body mass. On the other hand, both sexes of P. pangasius had relative weight average values of more than 100, simply indicates the fish is naturally obese and has enough stored energy to maintain its physiology. The calculated form factors suggested an elongated body shape, which is typical of many riverine fishes. In addition, a small number of morphological traits varied significantly in the current study. Likewise, in the case of morphometric features, the principal component analysis showed a considerable degree of connectedness between the male and female individuals. The blood values showed no significant difference between the sexes. This might result from feeding fish the same kind of food and maintaining them in the same environment. However, the higher temperature might have caused slight blood abnormalities in both sexes. The current findings strongly support raising this fish in captivity and would offer useful information for fish farm owners, entrepreneurs, stakeholders, and other concerns in Bangladesh and surrounding nations.

Retracing migration pattern in reproductive and non-reproductive female kutum Rutilus frisii, in south Caspian Sea, using otolith microchemistry

Because trace elements of otoliths are considered a natural marker capable of recognizing the chemical composition of ambient water and fish migration history, these elements could be potentially used to analyse the movement of reproductive (R) and non-reproductive (NR) mature-sized fish. Supposedly, it is not essential for NR individuals to migrate to rivers for spawning because they do not have developed gonads. To investigate the potential differences in migration history between female R and NR kutum, Rutilus frisii, in the southwest waters of the Caspian Sea, the ratios of Sr, Ba, Mg, Na, K and P to Ca in otoliths (from the core to the edge) were examined using laser ablation-inductively coupled plasma-mass spectrometry. In NR fish, a significant increase in Sr:Ca ratio in the otoliths' growth rings, likely due to greater seawater residency, and an increase in Ba:Ca ratio in the last two rings were observed. Increased Ba:Ca ratio could be due to the movement of NR mature-sized fish to the coastal zones for foraging. Seasonal physiological factors such as gonad maturation and spawning activity are more likely to be involved in differences in the other elemental ratios (Mg, Na, K and P). These results suggest that microchemical analyses of growth rings of otolith can be used as a valuable tool for better understanding the movement pattern of different types of adult fish, which could be completed with data from other methods like tagging.

Análisis morfométrico e índices corporales del capitán de la sabana (Eremophilus mutisii)

Con el objetivo de caracterizar la morfometría e índices corporales de Eremophilus mutisii, se usaron treinta y tres peces (27 hembras y 6 machos) provenientes del río Bogotá, específicamente de la región de Suesca. La relación de aspecto de la aleta caudal se determinó mediante el software de análisis de imágenes ImageJ®. Se calculó el índice gonadosomático, hepatosomático y rendimiento en canal para cada pez. Para el análisis de los datos se usaron correlaciones, regresiones y técnicas de análisis multivariado (análisis discriminante canónico). Como resultado del estudio se encontró que el sexo no afecta la forma del cuerpo de los peces. La relación entre la longitud y el peso se ajustó para cada sexo. La relación de aspecto de la aleta caudal presentó un promedio de 1,57 lo que sugiere que la especie presenta hábito sedentario o de natación lenta. El índice gonadosomático de las hembras en maduración (media: 14,43%, rango: 8,84% a 23,22%) aumentó en función del peso corporal y fue mayor que el de los machos (media: 5,32%, rango: 2,31% a 8,29%). Por lo tanto, el rendimiento de la carcasa fue menor en las hembras en maduración. La media del índice hepatosomático para hembras fue 0,86% (rango: 0,43% a 1,88%) y para machos fue 0,63% (rango: 0,39% a 1,09%). En conclusión, Eremophilus mutisii es una especie sedentaria y las hembras se caracterizarán por presentar mayor índice gonadosomático y menor rendimiento en carcasa que los machos.