Smart Aero-Spider: An adaptive and selective smart switching aerator system

The recovery from the COVID-19 pandemic hit shows the emergence of increase in quality of life across various parts of the world. With this lifestyle change, people are looking towards high quality food. Fish being a major source of protein, the industry producing fish from aquaculture is booming. The proposed smart aerator system provides an integrated array of underwater systems for selective aeration of the water body. The smart system ensures targeted aeration to guarantee optimal levels of dissolved oxygen at all times. This is beneficial for perfect survival, growth, and reproduction of fishes. The strategically placed spider aerators are turned on when readings from the dissolved oxygen level at the location is below the optimum range of values. The air blower system consists of an intelligent switching system to activate the right aerator based on the requirement. The sensor data is relayed to the cloud with a wireless communication module. This data can be used for useful insights and all-round monitoring of the water body. The respective aerators have IR sensor to detect movement alongside on-board LEDs to indicate functioning status. Overall, this ensures maximum accelerated growth of healthy fishes. Thus, the solution aims at efficiently boosting the ability of the aquaculture industry to meet the ever-growing demand of consumers.

An Overview of the Biological Features, Distribution, and Conservation of a Critically Endangered Riverine Catfish, Bagarius bagarius (Hamilton, 1822), in the Natural Waters of Bangladesh

Bagarius bagarius (Hamilton, 1822) is widely distributed in South and Southeast Asian countries, including Bangladesh. This species is economically important as a game and food fish. The abundance of this fish is declining around the world, especially in Bangladesh, due to a variety of meteorological and mostly anthropogenic factors, which is potentially generating concern among the conservationists. Therefore, this species has already been declared a critically endangered species by IUCN Bangladesh. Although there is no specific conservation initiative for B. bagarius in Bangladesh, various measures are there to conserve fisheries resources, which may have an impact on conserving B. bagarius in this country. This study reviews the biology and ecology with its distribution throughout the country as well as the world, threats, conservation measures, and finds out the gaps in research on this fish. Moreover, this review suggests a suitable conservation framework to improve the conservation strategy for this critically endangered fish that can be replicated in other countries for the same purpose.

Assessment of the growth performance and haematological indices of Clarias gariepinus fingerlings exposed to soap effluent

Background Various substances released from modern complex human societies which enter the aquatic ecosystems produce alterations in survivability of aquatic biota. This study assesses the consequence of exposure to industrial effluents containing potentially hazardous constituents, especially soap industrial waste effluent, relative to fish physiology, growth and survival, particularly food fish such as Clarias gariepinus. Five hundred (500) fingerlings of C. gariepinus (15.65 ± 0.02 g) randomly stocked at 50 fish per tank in duplicates were exposed to varying concentration (0, 0.32, 0.66, 1.31 and 2.63%) of homogenous effluent sample and fed Durante® floating feed at 5% of the body weight in two instalments per day for 180 days. The growth performance and feed utilization data were generated to determine the growth performance indices. The haematological parameters of the fish were also determined following routine methods of fish haematology. Result Generally, fish in the control had significantly (p < 0.05) better growth performance indices compared with the exposed fish. It was also observed that most of the significant increase or decrease observed in the growth performance was concentration dependent. Increase in HES concentration which significantly increases (p < 0.05) WBC count of the experimental fish was observed to decrease (p < 0.05) the HGB level of the fish. Significantly higher (p < 0.05) levels of RBC (3.02 ± 0.03 × 106/µL) and HCT (36.70 ± 1.68%) were recorded in the control fish. However, all the exposed fish had significantly higher (p < 0.05) levels of platelet count compared with the control. Conclusion This study concluded that exposure to concentrations of soap effluent induced stress, inhibited growth and altered the haematological indices of the exposed fish. Uncontrolled discharge of soap effluent into receiving water bodies, apart from affecting the wellbeing of an important freshwater food fish, there is every probability of possible accumulation of the chemical/toxic additives of the soap effluent which could have serious implications considering the man as the major and final recipient of these toxic bioaccumulated chemicals via the food chain and the environment.

Hazard Analysis of Trace Metals in Muscle of Sarotherodon Melanotheron and Chrysichthys Nigrodigitatus from Okulu River, Rivers State, Nigeria

Introduction: An instance of fish deaths in marine waters surrounding some communities in Bonny and Andoni Local Government Areas in Rivers State was reported in March-April 2020. This study investigated trace metals hazard in muscle of Tilapia (Sarotherodon melanotheron) and Silver Catfish (Chrysichthys nigrodigitatus) from Okulu River, Rivers State, Nigeria. Materials and Methods: Tissues of 24 samples of Sarotherodon melanotheron and Chrysichthys nigrodigitatus obtained from the river were analyzed using atomic adsorption spectrophotometer, and the health risk was estimated based on estimated daily intake (EDI), target hazard quotient (THQ), and total target hazard quotient (TTHQ). Results: The concentration (mg/kg) of iron, zinc, manganese, copper, cadmium, lead, and chromium in both species ranged 4.00 – 197.30, 9.20 – 35.30, 0.20 – 5.00, 0.00 – 73.10, 0.00 – 1.30, 0.00 – 54.70, and 0.00 – 0.50, respectively. The EDI of trace metals resulting from the consumption of both fish species was higher than the permissible tolerance intake (PTI) mg/day/60kg body weight. The THQ and TTHQ were < 1, indicating that the consumption of this food fish portends no known health concern. However, the carcinogenic risks exceeded the threshold level of 10-6 - 10-4, thus, reflecting carcinogenic tendency. Based on the results obtained, it must be ensured that the effluents discharged into open water bodies meet the recommended limits. Conclusion: There is a need to create awareness among consumers of food fish in the study area. There should be periodic monitoring of trace metals in surface waters and its food fish population to forestall potential health impact on humans.

Knowledge of, and Attitudes towards, Live Fish Transport among Aquaculture Industry Stakeholders in China: A Qualitative Study

China is the largest food fish producer in the world. Chinese consumers normally purchase fish that are still alive to ensure freshness. Therefore, the live transport of fish is important in China’s aquaculture, although it carries potential risks for animal welfare. This study investigated the attitudes and knowledge of stakeholders within Chinese aquaculture towards the live transport and welfare of fish. Semi-structured interviews were conducted with 12 participants who were involved with the aquaculture industry in China. Most participants self-rated their transport-related knowledge as moderate and had some understanding of animal welfare, although this term was generally considered only relevant to terrestrial animals. Participants’ responses indicated that the live transport of fish occurs frequently in China, generally using sealed tanks, plastic bags, and foam boxes, in purpose-built vehicles. Seasonal changes, such as changes in ambient and water temperature, are considered to be important contributors to successful live transport, as well as sufficient oxygen supplies and stocking density. The use of anesthetics was not commonly reported, particularly in food fish, and fish capture is predominantly by conventional dipnets. The health status of transported fish is determined mostly by morphology (body injury, body or eye color, and fin condition), as well as vigor and swimming ability. Our results indicate that live transport poses a number of welfare risks to fish but that participants in the process associated welfare concerns more with terrestrial animals, not fish.

Empowerment of Integrated Health Post Cadres through Fish Nugget Processing to Prevent Anemia in Pregnant Women

Fish is a source of nutrition that is cheap and easy to get, especially in Jember Regency. One of the health problems experienced by teenage girls and pregnant women is anemia. Anemia can be prevented by consuming adequate and diverse nutrients. However, the society at Darungan Dusun (Dusun is lower than the village in Indonesia's administrational hierarchy) did not know how to make exciting and not boring processed food. Fish nugget is creations from tuna or catfish to increase fish consumption coverage in society. This activity was carried out in the Integrated Health Post at Darungan Dusun Kemuning Lor Village, Jember Regency. There were fourteen of the integrated health post cadres and pregnant women who participated in this activity. Community service methods used demonstrations and counseling. The counseling and demonstration of fish nugget processing improve knowledge in Integrated Health Post cadres and pregnant women. Furthermore, it can prevent anemia in pregnant women. There should be support and participation from the local government for the sustainability of this activity.

Temporal Variations of Condition Factor and Relative Weight For Mystus Gulio (Hamilton, 1822) From the Coastal Water in Bangladesh

The long whiskers catfish, Mystus gulio (Hamilton, 1822), is a valuable, delicious food fish in coastal areas of Bangladesh. It is found in fresh and brackish water of South Asian region. The present study illustrates the temporal variation of condition factor (KF) and prey-predator through relative weight (WR) along with length-weight relation (LWR) of M. gulio in the Maloncho River at southern Bangladesh. There were a total of 1200 individuals collected between January-December 2017 and October 2019 to June 2020. Different traditional gears (such as cast net, seine net, square lift net) were used for collecting the fish samples. There were 35% males and 65% females. The total length of fish ranged 7.8-18.3 cm for males and 9.3-22.1 cm for females. The body weight ranged 8.80–72.34 g for males and 8.09-128.82 g for females. LWR was significant with r2 value >0.950. The calculated co-efficient (b) were negative allometric growth in male and female (b<3.0, p<0.001). The KF indicated the best condition of this species. WR revealed no significant difference from 100 for both sex (p = 0.441) and females (p = 0.221), indicating a suitable habitat for growth. From conservation point of view, the findings of this present study on M. gulio will be helpful in Bangladesh (Maloncho River) and neighboring countries. J. Bio-Sci. 29(1): 111-122, 2021 (June)

Morphometric Characters and Sex Ratio of the Freshwater Garfish, Xenentodon Cancila Collected From Different Waters of Jashore, South-Western Bangladesh

The freshwater garfish, Xenentodon cancila is one of the important food fish in Bangladesh. The size class distribution, length-weight relationships, and sex ratio of X. cancila are described in the present study. A total of 138 specimens were collected randomly for a year from the local fish markets and/or direct from fishermen who fish primarily in nearby waters (Beel, Canal and Baor) of Jashore, southwestern Bangladesh. Most individuals were collected in the rainy season and their mean size was larger compare to the other two seasons (summer and winter). The maximum size recorded 254.1 mm total length (TL) and 38.05 g body weight (BW). The mean TL and BW were 166.35±38.17 mm and 11.16±7.47g, respectively. Most of the individuals belonged to the size class of 141-180 mm. The length-weight relationship (LWR) was strongly correlated as the regression value was 0.876 and the relationships were linear in both sexes. The allometric coefficient ‘b’ of the LWR indicated nearly positive allometric growth and the value was 2.98. The male fishes were dominant over females and the ratio was 1: 0.77. These research outcomes would be useful for the researcher to better understand the biological aspects of freshwater garfish in the nearby waters of Jashore area in south-western Bangladesh. J. Bio-Sci. 29(1): 23-31, 2021 (June)