International Journal of Aquatic Biology
Volume:8 Issue: 4, Aug 2020

Silver pomfret, Pampus argenteus (Euphrasen, 1788) is one of the most valuable and desired table fishes of the world. It has high economic value and has been reported to contribute significantly in the commercial fishery in its native ranges. Considering its high economic value, it is really necessary to have scientific knowledge on its biology and culture so as to continue its fishery in long run. Substantial research has so far been conducted to gather information on its biology and culture, but till date no such consolidated report is available on these aspects. The present work has been focused to gather the already documented information on its biology and culture, and to point out the scope of further research to support its fishery and trade. Considering the information summed up in the present report, it is evident that ample information is available on its feeding and reproductive biology, but information on its culture methodologies is scanty. Hence, further study is needed to gather more information on its culture and rearing methodologies to support its fishery and trade in coming days.

In this study, the digestive tracts of the Caspian turtles (Mauremys caspica) were investigated for the presence of helminth infections. Specimens of roundworms were recovered from the large intestine and stomach of the Caspian turtles. The morphologic measures revealed the infection with nematodes of the genus Falcaustra and Spiroxys. However, some differences were found in the collected Falcaustra specimens compared to the previous descriptions. In parallel, samples were analyzed by sequencing of the ribosomal gene targets. The phylogenetic analysis showed that the Falcaustra species as members of superfamily Cosmocercoidea were grouped with some members of Ascaridoidea and Spiruroidea. Despite the significant morphologic differences, Spiroxys species formed a sister group with ascaroid and cosmocercoid roundworms. Therefore, our molecular findings revealed that the taxonomic position of both nematodes need be revised.

Present study was carried out to explore the morphological attachment devices od seven aquatic insect larvae or naiads (representing four orders of Ephemeroptera, Plecoptera, Trichoptera, and Hemiptera) along the swift water current of Binwa, a mid-Himalayan hill stream using scanning electron microscopy (SEM) images. Water current showed direct relation with slope/gradient and volume of water in stream. Samples were collected at four sites located at different attitude along the stream. The collected larvae or naiads have many morphological features, including adhesive pad, friction pad, serrated tarsal claw, bifid tarsal claw, tarsal claw with clamp, sucker, and serrated spines which serve as their adaptations for the fast-flowing waters. Principal Component Analysis revealed the importance of water current for assemblage and abundance of these aquatic insects, as it directly related to TDS, electric conductivity, turbidity and nutrients level in stream water, and cumulatively affect these aquatic macroinvertebrates. Similarities in structures of different species suggest the convergent evolution, while slight differences inferred as specializations for species specific niche of these organisms in stream habitat.

This study is the first to compare age estimates based on scales and otoliths of the Nile tilapia, Oreochromis niloticus, from Lake Nasser, Egypt. Ageing precision between readers was estimated by calculating the percent agreement between three independent readers, and the coefficient of variation (CV) ages estimated from otoliths and scales. The relation between the total length of fish and the radius of its scale and otolith was determined and appeared to be linear. The estimated age composition of the O. niloticus included six age groups estimated using scales and five age groups estimated by otoliths. The relative precision (CV and SD) of ages estimated from otolith was higher than that from scales. Higher percentages of agreement of overall annuli identification and age assignment between readers were noted in otoliths comparing to that in scales. Scale showed some inaccurate estimation in the age of fish older than 4. The precision and bias information in this study will be beneficial to fisheries professionals in assessing the age of Nile tilapia and other cichlids in the future.

Invasive peacock bass Cichla spp. have recently invaded freshwater habitats across Malaysia. Stomach contents of 135 peacock bass captured from the Telabak Lake of East Coast of Peninsular Malaysia were analysed. The preys were examined using visual identification method and mitochondrial DNA barcoding technique to identify the partial digested and decaying preys in the stomach. The current study identified 7 prey species (6 fishes 43.0% and 1 shrimp 5.1%) belongs to 5 families in fishes’ stomach. The results revealed that peacock bass is highly predator and generalist feeder with an opportunistic feeding behaviour. It is highly important to reduce and monitor the abundance of this species for future survival of native species in the lake.

The Caspian kutum (Rutilus kutum Kamensky, 1901) is an important economic species in the southern, uniquely Iranian waters of the Caspian Sea. The present study aimed to assess the desirable levels of the Caspian kutum for stock enhancement with two scenarios using fingerlings released (FR) and recruitments (R) density-dependence and macrobenthic production (P). Based on the results, in the years 1989-2018, the FR increased from 72 million in 1989 to 400 million in 2009 and then declined to 176 million in 2018. In contrast, the R with a lag of 2 years declined from 44.53 million in 1991 to 25.77 million in 1998, increased to 65.07 million in 2005, and then collapsed to 25.01 million in 2018. Based on FR-R relationships of Ricker and segment regression models, the lowest level of FR, which resulted in the highest R (39 million), was about 200 and 150 million fingerlings, respectively. Based on the P/Biomass ratio of macrobenthic species, the annual production was 241.6 thousand mt. It concluded that the desired number of the Caspian kutum fingerling concerning stock enhancement could be lower than 150 million to prevent overcompensation in the Iranian waters of the Caspian Sea.

An eight-week feeding trial was conducted to investigate the effects of different levels of dietary chamomile (Matricaria recutita) aqueous extract (CAE) on growth performance and antioxidant status of zebra fish, Danio rerio. Fish (initial weight of 0.20±0.02 g) were stocked at 12 tanks (50 fish per tank) and fed with a basal diet (32% protein and 8% lipid) supplemented with 0 (control), 0.5, 1, and 2% CAE in triplicate groups for 8 weeks. The results showed that fish fed 2% CAE had a significantly higher growth and biomass gain compared to the control group (P<0.05). Condition factor had a significant increase in 2% CAE treatment compared with other treatments (P<0.05). There were no significant differences in catalase, glutathione peroxidase, and superoxide dismutase activity amongst treatments (P<0.05). Finally, it seems the use of a 0.5-2.0% CAE can be effective in improving the growth and antioxidant system of zebra fish,

Minke whale, a member of the Sub order Mysticeti, was sighted stranded in the northern, and southern parts of eastern Mediterranean. This paper report stranding of a Minke whale in Banyas Coast of Syria, and fills the gap of the species distribution between the north and south of the eastern Mediterranean.