The disease caused by carp edema virus (CEV) manifests with lethargy as a primary sign; this observation in koi in Japan gained the disease the name koi sleepy disease (KSD). In the years following the discovery of the virus in Japan, KSD cases have been noted in the UK in koi and common carp. Conducting research in order to expand knowledge of the processes of distribution of CEV in infected fish organs will be helpful for eradication and diagnostic purposes.

In this study, the detection of biogenic amines in fresh and products of fish is focused and biological trials have been used to reduce their levels. 120 random samples of fresh fish (Lates niloticus), sardine salted, herring smoked, and tuna canned (for every thirty samples) were collected from different markets in Shibine, Menoufia, Egypt. The biogenic amine residues have examined in all samples that were collected (histamine, putrescine, cadaverine and tyramine). The average levels of biogenic amines in the samples under investigation of fresh fish, canned tuna, herring smoked, and sardine salted are 10.74 ± 0.54, 15.08 ± 0.76, 17.93 ± 0.81 and 26.12 ± 0.89 mg % for histamine, 7.61 ± 0.49, 11.13 ± 0.57, 14.35 ± 0.64 and 19.59 ± 0.81 mg% for putrescine, 5.96 ± 0.43, 10.22 ± 0.49, 12.41 ± 0.58 and 16.85 ± 0.62 mg% for cadaverine each, accordingly. Finally, the tyramine mean value was 2.05 ± 0.10 mg % in fresh fish, 6.37 ± 0.19 mg % in tuna canned, 7.9 ± 0.24mg % for herring smoked and10.44 ± 0.27 mg % for sardine salted. Fish fillets were experimentally inoculated with B. polymyxa culture (2x107), the effect was ideal, the level of histamine reduced to 31.4 mg/kg after eight hours, 19.5 mg/kg after 12 hrs and 12.8 mg/kg 24 hours later with reduction percentages of 37.2%, 61.0%, and 74.4%, respectively and cadaverine level reduced to 22.1 mg/kg after 8 hours, 15.4 mg/kg after 12 hrs and 9.7 mg/kg 24 hrs later with reductions percentages were 26.3%, 48.7%, and 67.7%, respectively.

Fish is one of the most important foods because of its high nutritional value, high palatability, and easy digestion. At the same time, it acts as a vehicle for many types of pathogenic microorganisms especially Aeromonas species, which results in public health hazards. Therefore, the present study was conducted to evaluate the prevalence of Aeromonas species in fresh fish (catfish, mullet, lizardfish, and coralfish) marketed in Zagazig city, Sharkia Governorate, Egypt. In addition, multiplex PCR was performed to detect some virulence-associated genes in A. hydrophila isolates. Furthermore, antimicrobial susceptibility testing was carried out on A. hydrophila isolates using commonly used antimicrobials in Egypt through the disc diffusion method. The achieved results indicated contamination of fish with different species of Aeromonas such as A. veronii, A. sobria, A. caviae and A. hydrophila. The results revealed that Aeromonas species isolated with an overall percentage of 55% of all examined fish. Bacteriological examinations revealed 20% A. hydrophila, 20% A. sobria, 10% A. caviae and 5% A. veronii. Antibiotic sensitivity declared high resistance of the isolates to different antimicrobial agents used in Egypt, including penicillin (100%), Ampicillin (90.0%), Streptomycin (90.9%), Cephalothin (72.7%), Tetracycline (72.7%), Cefotaxime (63.6%), and Sulfamethoxazole (54.5%). Therefore, hygienic measures should be adopted to control microbial contamination either in the aquatic environment or in fish markets.

Pseudomonas aeruginosa (P. aeruginosa) is a psychotropic pathogenic bacterium that is considered one of the most common spoilage microorganisms related to seafood’s consumption. P. aeruginosa is widely distributed in nature and isolated from soil, plants, animals, and water. Because of its high resistance to a wide range of antibiotics, P. aeruginosa is more dangerous than other spoilage bacteria. It possesses a diverse set of virulence factors capable of causing severe and aggressive infections in humans and animals. Antibiotic resistance genes are easily transmitted to humans via contaminated seafood, resulting in a serious antibiotic resistance.  The ability of P. aeruginosa to form a biofilm maintains its environmental survival and allows its quick adaptation to harsh environments. Therefore, for the benefit of customers and public health globally, the safety and bacteriological quality of commercially processed fish and its products are crucial.

Fish and fish products represent major contributors to supply humans with part of their needs of the essential amino acids, vitamins, minerals, omega -3-fatty acids, and other needed micronutrients. However, fish and fish products are highly perishable foods that can easily spoiled and decomposed, possibly because of its cross contamination from the surrounding environment. Fish attracts a vast array of microorganisms, of these; mould and yeast represent a major sector of these microbiota, which by turn van lead to rapid decomposition of fish or even produce several toxicological implications if ingested. In this review, we will highlight the available literature about mould contamination of fish and fish products with a special reference to its public health significance.

The purpose of the study was to verify the existence and pathogenicity of Aeromonas hydrophila (A. hydrophila) in fish by validating the bactericidal effects of microwave and Gamma radiation on infected fish fillets. A total of 100 frozen Basa fish fillet samples were collected randomly from different markets in Zagazig, Sharkia Governorate, Egypt, and subjected to microbiological examination. The results revealed a 14% prevalence rate of A. hydrophila in fish fillets, which were tested for the presence of seven virulence genes: aerA, act, ast, alt, hyl, ahhR, and ahh1. All isolates exhibited traits related to virulence. The most predominated gene was ast (64.2%), followed by aerA, act, hyl, and ahhR (57.14% for each). Then, an experimental protocol for several treatments showed that Gamma radiation at a dose of 1 kGy decreased the count of A. hydrophila in fish fillets by 4.4 log10 CFU/g whereas doses of 2 and 3 kGy eradicated the pathogen. The same positive effect was recorded towards the microwave after cooking for 1, 2, and 3 minutes. Therefore, using microwave cooking and Gamma-irradiation alone and in combination with other decontamination methods may be more efficient in lowering the pathogen counts in fish meat.

In the aquatic environment, pollution with heavy metals is a major issue. Some of them are essential heavy metals because they play biological roles for aquatic organisms. Other heavy metals, however, are regarded as dangerous even at low concentrations. Heavy metal levels that are harmful may be caused by industrial, mining, and agricultural operations. Water contamination and changes to the physicochemical properties of the aquatic environment will result from this. The harmful toxic consequences of this pollution on fish raise questions about its possible impacts on human health. The most prevalent heavy metals are arsenic, cadmium, lead, and mercury, which are systemic toxicants and have an impact on human health. These metals are classified as carcinogens by the United States Environmental Protection Agency and the international agency for research on cancer because they cause organ damage even at low exposure levels. This review was created to contribute to the understanding of the environmental impact, toxicology, and consequences of heavy metals on fish.