Journal of Applied Ichthyology最新文献

The aim of this study was to evaluate different aspects of larviculture of Persian sturgeon (Acipenser persicus). With this regard, the growth performance, e.g., final weight, specific growth rate (SGR), and cannibalism rate of Persian sturgeon were assessed. The study was performed using two separate strategies; size heterogeneity and feeding/fasting strategy (experiment-A), besides implementing stocking density (experiment-B). In the experiment-A, twelve circular tanks (9.6 L) were considered as following: A₁ (5 large starved fish +5 small starved fish); A₂ (5 large fed fish +5 small fed fish); A₃ (all 10 large starved fish); A₄ (all 10 large fed fish); A₅ (all 10 small starved fish) and A₆ (all 10 small fed fish). In experiment-B, the stocking density was doubled for all groups in the same tanks: B₁ (10 large starved fish +10 small starved fish); B₂ (10 large fed fish +10 small fed fish); B₃ (all 20 large starved fish); B₄ (all 20 large fed fish); B₅ (all 20 small starved fish) and B₆ (all 20 small fed fish). Data were collected at the end of the 7th and 14th days. Growth performance increased significantly in all fed treatments of experiment-B in comparison to starved treatments (P < 0.05). The highest final weight and SGR was observed in B₂ (363.5 ± 130.1 mg in 14th day) and B₆ (26.5 ± 1.0% day⁻¹ in 7th day), respectively. Cannibalism rate was increased in Persian sturgeon larvae maintained at low density, in which the highest rate was observed in the starved groups (A₁ [27.5%], A₃ [35.0%], A₅ [40.0%]). Size heterogeneity leads to disappear/die all small larvae, in both low- and high-density only in the starved group, regardless of size, died at the end of the second week. In conclusion, in Persian sturgeon, cannibalistic behavior is more affected by stocking density. To manage larviculture of this species, optimizing the stocking density to prevent the cannibalistic interaction, besides having continuous feeding is a paramount.

In a 56-day feeding trial, the effects of dietary inclusion of four fibre-rich-leaf meal-based diets (Napier, alfalfa, Gliricidia, or Ipomea) on growth, haemato-biochemical parameters, and histology of the intestine, liver, and kidney in hybrid lemon fin barb fingerlings were investigated. Each of the leaf meals was included at 10 g 100 g⁻¹ in five dietary treatments. As a control, a diet with no leaf meal was used. Each diet was randomly allocated to three tanks and the hybrid fish were also randomly stocked in 60 L glass tanks at 15 fish per tank. When compared to the control group, the leaf meal-treated groups performed better in terms of growth, which was significantly (p < .05) higher with Ipomea- and Napier-fed groups. Ipomea-fed fish had the best performance among the leaf meal groups. The leaf meal-based groups had numerically greater haematological profiles than the control fish but shared statistical similarities (p > .05) with the control group. The PCV, RBC, Hb and WBC levels in fish fed an Ipomea-based diet were the highest. The serum biochemistry of fish fed different dietary treatments showed significant differences (p < .05). With the exception of the fish fed Ipomea, there were statistical similarities (p > .05) in the total protein, albumin, and globulin contents between fish fed the leafmeal-based diets and control diets. The intestinal morphology of fish fed test leaf meal-based diets was normal. The livers of fish given the test leaf meal-based diets showed moderate to severe widespread vacuolization of the hepatocytes, as well as localized nuclei, with very slight erosion of the mucous membrane at the tips of the villi.

Thermal tolerance is crucial to understanding the biology of fishes and their responses to changes in temperatures, such as that produced by climate change. Shortnose sturgeon (Acipenser brevirostrum) is an endangered species (USA) and a species of special concern (Canada) that live on the eastern coast of North America. Although previous studies have focused on the acute critical thermal maximum (CT_max) of shortnose sturgeon, nothing is known with respect to their acute critical thermal minimum (CT_min) and the overall thermal tolerance of this species. This study examined the upper (CT_max) and lower (CT_min) thermal tolerance of shortnose sturgeon acclimated to 12 and 18°C. CT_max increased with increasing acclimation temperature; however, there was no significant relationship between acclimation temperature and CT_min. Taken together, the results of the present study show that shortnose sturgeon are well adapted to tolerate acute exposures to both cold and warm water environments.

Five specimens of Oman gurnard, Lepidotrigla omanensis (58.7–64.4 mm standard length), distributed widely in the Western Indian Ocean, including Somalia, Oman, Pakistan, Southwest India, and Myanmar, were collected at Patharghata (Barguna district) and Swarupkati (Pirojpur District) fish markets in Bangladesh between March and May 2020. The specimens were caught in the Bay of Bengal. The collected specimens were confirmed as L. omanensis by observing the morphological features: a blade-like spine at each corner of the upper jaw, a lateral line with 54–62 pored scales, a pectoral fin reaching the 5th to 7th anal fin rays, the first dorsal fin with a large red blotch covering the distal third to sixth spine, and the structure and position of opercular and cleithral spines. Previously, four gurnard species have been reported from the coastal waters of Bangladesh. However, the current study's latitudinal range extension of Oman gurnard demonstrated the potential role to enrich the fish diversity in the Northern Bay of Bengal. A detailed description of the specimens was provided, and intraspecific variations among the specimens of same genus available in the reported area were documented and compared.

The present study provides the length–weight relationships (LWRs) for common estuarine fish species collected from the Yangtze River Estuary by bottom trawl from 2017 to 2021. The net port width of bottom trawl net was 6 m, and the mesh size was 20 mm. This study provides new information on LWRs for three species in FishBase. Also, this study updates the information on the maximum length for three species.

Cobitis faridpaki is a small endemic loach from the southern Caspian basin. Reproductive parameters are key components for enlightening the life history of an endemic species. The reproduction parameters of C. faridpaki including sex ratio, spawning season, fecundity, and oocyte diameters were studied in a tributary of Gorganroud River – northern Iran, the area where no information on the Cobitis spawning is available, from February to July 2018. A total of 403 specimens including 47.8% males and 52.2% females were collected using electrofishing. Even though the sex ratio was not significantly different from parity, a perceptible dominance of females in the pre-spawning and spawning periods could be observed in the population. Based on the monthly variation in GSI, the spawning period is from late March to early May. The absolute fecundity of females ranged from 57 to 1287, with a mean of 404 (±250) oocytes per ovary, and relative fecundity was estimated to be 47–386, with a mean of 136 (±73) oocytes per gram of total weight. Absolute fecundity established statistically significant linear relationships with total length and weight. Oocyte diameters varied from 0.26 to 1.30 mm, being of multi-modal distribution throughout the spawning period, which suggests that the species is a multispawner. The oocyte size correlated positively with the length, weight, and age of mature females. This study provides fundamental information to aid in future conservation programs that intend to reduce the ongoing depletion of habitats and populations of endemic species.

Length-weight and length-length relationships (LWRs and LLRs) for eight species of sharks were estimated using fish specimens caught in commercial fishery during 2018–2021 and landed at three fishing ports (Tanjung Luar Fish Landing Port-Lombok, Muncar Coastal Fishing Port-Banyuwangi and Sungai Kakap Fish Landing Port-Pontianak). The LWRs for Hemipristis elongata, Lamiopsis tephrodes and Pseudocarcharias kamoharai as well as the LLR for P. kamoharai reported in this study have not appeared on FishBase. This study also improved the LWRs and LLRs for other species. In addition, this study updated the maximum total length records for Carcharhinus brevipinna, Hemigaleus microstoma, H. elongata, Hexanchus nakamurai and L. tephrodes.

Recent studies have incorporated behavioural aspects into the analysis of animal invasion processes, citing high activity and boldness as typical traits of successful invaders. The topmouth gudgeon Pseudorasbora parva is arguably the world's most widespread freshwater fish invader currently listed as a pest species on the list of invasive alien species of Union concern. The study aimed at elucidating whether behavioural traits of P. parva contribute to its invasive success. Laboratory experiments contrasting P. parva activity levels, habitat choice and boldness with that of native competitors Eurasian perch Perca fluviatilus and three-spined stickleback Gasterosteus aculeatus showed P. parva to be relatively shy and avoiding direct competition for prey. An additional field study in a pond in central Germany demonstrated that P. parva was able to establish and maintain a small population, co-existing with a much higher density of P. fluviatilis. The study suggests that the invasive success of P. parva may be a result of its flexible life-history traits, while behavioural traits such as boldness and competitive dominance for food may only play a minor role.

High density fingerling rearing of pengba, Osteobrama belangeri in biofloc system was carried out for 45 days with wheat flour and molasses as two carbon sources to maintain C/N ratio of 15:1. Effect of biofloc was evaluated in terms of water quality changes, fish growth performance, digestive enzyme activities, non-specific immune system and antioxidants enzyme activities. Use of the two carbon sources ensured prevalence of better growing environment, higher digestive and antioxidant enzymatic activities, ultimately leading to higher fish growth, as compared to control. Further between the two carbon sources, use of wheat flour caused significant increase in the activities of digestive enzymes, amylase and total protease (p < .05); antioxidant enzymes such as SOD and catalase; increase in serum total protein, albumin and globulin, as compared to molasses, ultimately leading to higher growth. However, non-specific immune parameters such as respiratory burst activity in blood, lysozyme activity, and myeloperoxidase activity in serum were higher (p < .05) in fish reared with molasses. Such result while indicated benefits of additional carbon source, it also revealed wheat flour to be a better source for carbon supplementation than molasses in biofloc system during the high-density fingerling rearing of O. belangeri.