BACKGROUND: Tilapia, Oreochromis niloticus, is an omnivorous and important breeding species in the world. Over the recent years, tilapia breeding has begun in Iran. In aquaculture, it is very important to regulate a balanced diet in terms of nutrients needed for growth, which would be also economically appropriate.OBJECTIVES: The main objective of this study was to investigate the effect of substituting chicken waste powder in the diet of fish at levels of 0, 25, 50, 75, and 100 % on the tissue structure of different parts of the intestine of Nile tilapia.METHODS: 75 fish (three frequency per treatment) were fed with chicken waste powder instead of fish meal in their diet for eight weeks at 0, 25, 50, 75, and 100 % levels. At the end of the treatment, separate samples were taken from the initial, middle, and end parts of the intestine. After passing the usual histological steps, the slides were assessed by hematoxylin-eosin staining and TUNEL immunohistochemistry technique.RESULTS: In histometric studies, the highest villi height, thickness, muscle layer, and number of goblet cells were reported in the control group and the lowest in the 100 % group. In immunohistochemical studies, the number of apoptotic cells in groups 75 and 100 % was higher than that in the other groups.CONCLUSIONS: According to the results of the present study, it could be suggested that the replacement of chicken waste powder instead of a fish meal up to 50 % for indigo tilapia is tolerable. However, higher levels of chicken waste powder will reduce absorption, and acceptance of food and have adverse effects on growth.

This study was carried out to evaluate the bacteriological status of fresh Tilapia nilotica, fresh Clarias lazera, frozen Mackerel and smoked Herring fish marketed in Beni-Suef City. The collected samples were examined for total bacterial count, coli form (MPN), faecal coli forms (MPN), E. coli (MPN), Staphylococcus aureus count, total proteolytic count, total lipolytic count, Aeromonas count and Pseudomonas count, as well as the isolation of E. coli, Staphylococcus aureus, Aeromonas hydrophila, Pseudomonas aeruginosa, Yersinia enterocolitica and Listeria monocytogenes. Most of the examined samples were within the permissible limits recommended by EOS and ICMSF, few samples of fresh Clarias lazera exceeded the recommended limits. The economic importance and public health significance of the isolated organisms were discussed.

Fish and fish products are highly nutritional food that spoiled rapidly. Moreover consumer needs for natural preservatives instead of synthetic ones have increased. So, the aim of this study was to evaluate the natural preservation effects of sage (Salvia officinalis) and garlic (Allium sativum) essential oils on the shelf life, sensory attributes, chemical quality, and bacteriological quality of chilled fish balls (Kofta). It was found that shelf life and sensory attributes of those group treated with garlic 2%, sage 2%, and mixtures (garlic: sage) has increased till the 15th day of chilled storage compared to control group (untreated) that rejected on the 6th day of storage. Examined EOs showed marked antioxidant efficacy that delayed chemical deterioration of tilapia fish kofta. Moreover, antibacterial impacts of EOS were detected by reducing total bacterial counts, Psychrotrophic count, Pseudomonas count, Aeromonas count, and Staphylococcus count. It was concluded to that using EOs especially garlic and/or sage is a promising solution to overcome risk of chemical preservatives.

Streptococcosis is a zoonotic bacterial disease in tilapia and other fresh that creates economic losses, caused mainly by Streptococcus agalactiae and Streptococcus iniae. The hazard of the disease is that it may present apparently healthy as well as its presence in culture water. So, this work aimed to detect streptococci in Nile tilapia farms located in Assiut and Minia Governorates, Egypt. Streptococcus agalactiae (42 isolates) and Streptococcus iniae (59 isolates) were identified. Two Streptococcus agalactiae isolates were molecularly confirmed and exhibited resistance to most antibiotics and a multiple antibiotic resistant index of 0.9-1. The identified isolates could not form biofilm. Identification of these hemolytic, resistant Streptococcus poses a potential hazard for human health; hence, alternative antimicrobials should be searched against infections caused by these bacteria.

Water quality is an important part of any aquaculture system. Water provides aquatic animals with oxygen, allows for waste removal, and is the conduit for their food. Similar to all other organisms, fish are heavily influenced and dependent on the characteristics of their environment. Non-optimum water physicochemical parameters as dissolved oxygen, pH, salinity, ammonia, temperature etc. can cause stress to the cultured fish and thus make them more susceptible to disease outbreaks. Nile tilapia is the most cultured fish in Egypt. While its sustainable production is hindered by many obstacles. One of them is the water quality, therefore the hygienic effects of the water parameters are important to be clear in culturing.

Water quality is an important part of any aquaculture system. Water provides aquatic animals with oxygen, allows for waste removal, and is the conduit for their food. Similar to all other organisms, fish are heavily influenced and dependent on the characteristics of their environment. Non-optimum water physicochemical parameters as dissolved oxygen, pH, salinity, ammonia, temperature etc. can cause stress to the cultured fish and thus make them more susceptible to disease outbreaks. Nile tilapia is the most cultured fish in Egypt. While its sustainable production is hindered by many obstacles. One of them is the water quality, therefore the hygienic effects of the water parameters are important to be clear in culturing.

Fish is considered as important source of animal derived protein, omega-3-fatthy acids, minerals such as calcium, phosphorus, iodine, and vitamins. Among the fish species, tilapia nilotica is the most famous fish in Egypt due to its ease culturing, short production cycle, cheap price, and therefore play fundamental roles in food security, particularly in the human supply of the anumal-derived protein. Fish during its production till delivery to the consumer's table might be exposed to a vast array of microbial contaminants either originated from its surrounding eniveronment or via cross contamination from the angler's hands, during transportation, and storage. Therefore, tilapia might act as a potential source of spreading of foodborne pathogens to the consumers. However, few reports had investigated the microbal quality of tilapia, particularly in Egypt. Therefore, this review was undertaken to report literatures studying the prevalence of some foodborne pathogens in tilapia fish in Egypt, the factors that affect the microbial quality of the fish, and some recommendations in order to extend the shelflife and improve the microbial quality of Tilapia nilotica. This reviw concluded that tilapia is eligible for contamination with a vast array of microorganisms such as enterobacteriacae, Staphylococcus aureus, Shewanella putrefaciens, Corynebacterium urealyticum, Aeromonas hydrophila, and Flavobacterium spp. Therefore, it is highly recommended to have efficient cooking of fish either via boiling, grilling, panfrying, dipping in liquid smokes, irradiation, ozonization, and addition of smone natural addirives such as lemon juice.

The main aim of the Egyptian government is not only to increase tilapia fish production, but also to improve the quality of the fish produced. Contaminated water causes damage to farmed fish and is also considered an important factor affecting the fish quality. To avoid losses in fish farms, it is critical to obtain information on the microbial load. This research aimed to study the microbial load in four fish farms in the governorates of Kafr El-Sheikh and El-Faiyum (two farms in each governorate), in Egypt. Water and fish samples were collected at various locations within each farm pond for two seasons (autumn and spring) to assess the microbiological characteristics. Total coliform count of aquaculture water samples was the highest mean count of 3.93×103±1.81×103 CFU/ml in farm (3) of El-Faiyum. However, Clostridium counts were highest in farm (2) of Kafr El-Sheikh at 1.85×102 ±1.76×102 in autumn of 2021. Total coliform count (1.196×103±8.38×102) was the highest in farm (1) of Kafr El-Sheikh in spring 2022. Also, Salmonella spp. was only detected in farm (2) of Kafr El-Sheikh in autumn 2021, but in spring 2022 it was positive in farm (3) of El-Faiyum. Nevertheless, Listeria spp. was not detected in the aquaculture water samples examined. In addition, Salmonella spp. was detected in farm (1) of Kafr El-Sheikh and in farms (3 and 4) of El-Faiyum in spring 2022. It was concluded that the presence of pathogenic bacteria such as Staphylococcus aureus, Salmonella and Clostridium in fish samples in some farms in Kafr El-Sheikh and El-Faiyum may contribute to foodborne illness. So that, the microbiological criteria are recommended to be applied as guidelines to develop additional control programs in fish farms. This can help in the pollution control of the agricultural drainage water that is used in aquaculture; consequently, prevent the growth and toxin production by pathogens

Objectives: Streptococcus agalactiae is a zoonotic human and animal pathogen that causes global economic losses in aquaculture and fatal outcomes in Tilapia. This study aimed to identify S. agalactiae isolated from different fish sources intended for human consumption phenotypically and genotypically and to characterize the virulence-associated genes fbsA (fibrinogen-binding protein FbsA), cfb (CAMP factor), and pbp1A/ponA (penicillin-binding protein 1A). Materials and Methods: Three hundred Nile Tilapia fish (Oreochromis niloticus) were collected from different farms and retail shops in Dakahlia and Damietta, Egypt, during the summer of 2020. The samples were examined using routine phenotypic methods, then characterized using polymerase chain reaction (PCR) targeting S. agalactiae-specific dltS gene. All S. agalactiae isolates were examined for the susceptibility to ten antimicrobial agents by the disc diffusion method. The virulence-associated genes (fbsA, cfb, and pbp1A/ponA) were characterized using multiplex-PCR. Results: Streptococcus agalactiae was detected in 7% (n = 21/300) samples. The isolates showed high resistance against ampicillin and erythromycin (20/21; 95%) for each. The most predominant antibiotypes through isolates were P, CN, SXT, CRO, TE, CTX, E, AMP, at 10.5% for each antibiotype. A total of 19 (90.5%) of S. agalactiae isolates showed multi-drug resistance (MDR), and those were recovered from market Tilapia fish. The virulence-associated genes (fbsA, cfb, and pbp1A/ ponA) were identified in the S. agalactiae as 100%, 76%, and 52%, respectively. Conclusions: The MDR S. agalactiae detected in raw Tilapia fish pose a significant health hazard to consumers due to their zoonotic characteristics. [J Adv Vet Anim Res 2022; 9(1.000): 95-103]