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.

A total of one hundred samples of marketed fish farm; 25each of tilapia (Oreochromis niloticus), Mugil cephalus, Carp (Silver) and fry; were collected from different localities at Al- Behera and Kafr El-Shakh Provinces. The samples were examined for detection of testosterone hormone by Thin Layer chromatography (TLC) as well as it was quantitatively assayed by Radio-Immuno-Assay (RIA). The obtained result revealed that the testosterone residues were detected in flesh of farm fish of Tilapia (Oreochromis nilotocus) and Carp (Silver), each constituting 24% and 4 %; respectively but it could be failed to detect in each of Mugil cephalus and fry. The hormonal residues of testosterone was ranged from 3.25 to 34.9 ng/g with mean value 4.22±1.1 ng/g in positive samples of Tilapia, while only one sample of Carp showed 22.0 ng/g, Mugil cephalus and Fry showed no detectable level of hormonal residues. The public health significance of detectable levels was discussed as well as the recommendations to avoid health hazards from such fish were mentioned.

The present study deals with a monogenean parasite infecting, some marine fish through light and scan electron microscopy. It revealed that the percentage of infection was 48% (14 out of 50 fish), 28% (14 out of 50 fish), 22% (11 out of 50 fish) and 16% (8 out of 50 fish) in Diplodus noct, Gerres oyena, Lethrinus elongates and Siganus revulatus, respectively. The present work recorded Paranaella diplodae (Polyopisthocotylea; Microcotylidae; Monogenea) as a new species collected from the investigated fish gills. They are lanculate flukes, the haptor is not distinguished from the body proper approximately 1/3 of the whole body length. The surface topography of the parasite bears small pits and conspicuous transverse folds and richly supplied with papillae-like unicellate sensory ending. The opisthohaptor is typical of Microcotylidae. The clamp structure and the haptoral tegument are similar to the rest of the body

Carp oedema virus (CEV) is a relatively understudied poxvirus. It exhibits an affinity for gill and skin epithelial cells. Investigations were conducted into selected aspects of CEV biology, with a focus on determining cell and tissue tropism of CEV, acquiring gene sequences and updating CEV tests in fish tissues.

Herpesviruses are common agents in animals of the aquatic environment. They infect many species of fish but only lead to disease in one or two species. Nevertheless, infected fish without clinical symptoms can actively transfer infectious agents to disease-susceptible species. The aim of the study was to identify and prove the natural presence of different herpesviruses.

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.

Nontuberculous mycobacteria (NTM) are increasingly recognised as causative agents of opportunistic infections in humans for which effective treatment is challenging. There is very little information on the prevalence of NTM drug resistance in Poland. This study was aimed to evaluate the susceptibility to antibiotics of NTM, originally isolated from diseased ornamental fish. A total of 99 isolates were studied, 50 of them rapidly growing mycobacteria (RGM) (among which three-quarters were Mycobacterium chelonae, M. peregrinum, and M. fortuitum and the rest M. neoaurum, M. septicum, M. abscessus, M. mucogenicum, M. salmoniphilum, M saopaulense, and M. senegalense). The other 49 were slowly growing mycobacteria (SGM) isolates (among which only one was M. szulgai and the bulk M. marinum and M. gordonae). Minimum inhibitory concentrations for amikacin (AMK), kanamycin (KAN), tobramycin (TOB), doxycycline (DOX), ciprofloxacin (CIP), clarithromycin (CLR), sulfamethoxazole (SMX), isoniazid (INH) and rifampicin (RMP) were determined. The majority of the isolates were susceptible to KAN (95.95%: RGM 46.46% and SGM 49.49%), AMK (94.94%: RGM 45.45% and SGM 49.49%), CLR (83.83%: RGM 36.36% and SGM 47.47%), SMX (79.79%: RGM 30.30% and SMG 49.49%), CIP (65.65%: RGM 24.24% and SGM 41.41%), and DOX (55.55%: RGM 9.06% and SGM 46.46%). The majority were resistant to INH (98.98%: RGM 50.50% and SGM 48.48%) and RMP (96.96%: RGM 50.50% and SGM 46.46%). The drug sensitivity of NTM varies from species to species. KAN, AMK, CLR and SMX were the most active against RGM isolates, and these same four plus DOX and CIP were the best drugs against SGM isolates.

Many consumers seek long-ripening meat products. The availability of these highly distinctive cured pork varieties is continuously expanding and their safety should be subject to monitoring. One of potentially harmful substances in these products is histamine. The presence of this toxic amine is reported in many countries, even in high concentrations. However, the EU has not regulated the permissible histamine content in meat, in a situation at odds with that of regulated fish and fish products. This study established the usefulness of biogenic amine testing in long-ripening pork and furnished indicative concentrations potential useful as a background for future research in preparation for EU regulative intervention. A total of 97 samples of long-ripening meat products untreated by heat were bought from various shops in the Puławy and Lublin regions of Poland and tested for the presence of histamine using high-performance liquid chromatography with diode array. The histamine concentration ranged from below limit of detection to 346.64 mg/kg, where 3.47 mg/kg was the lowest in a positive sample. Histamine was detected in 48 samples (49.5%). The maximum amount of histamine was identified in dry ham and the minimum in traditional salami. The results of this study suggest that testing meat products for biogenic amines should be a very good indicator of the food safety of long-ripening meats. In half of the tested products, levels of biogenic amines potentially toxic to consumers were determined.

Koi herpesvirus (KHV) has infected farmed common carp in Poland clinically and asymptomatically since 2004. The role of non-carp species as vectors of virus transmission is well known except for in the case of KHV. The aim was to better understand this virus’ infection and transmission pathways in common carp, looking at the potential vector role of fishes kept with them. Eight species were experimentally infected with KHV by immersion in a suspension at 20°C ±1 and transferred to a tank after 45 minutes. Specimens were euthanised at intervals up to 56 days post infection (dpi) and tissue was examined for KHV DNA. Surviving infected fishes were introduced at intervals, each time into a separate tank, to naïve common carp for experimental infection. These were observed daily for symptoms, sacrificed along with controls after three months, and dissected to provide tissue samples. Also fish from 14 species collected from a farm with a history of KHV were sampled from 3 to 22 months after disease was confirmed. Organ sections from single fish were collected in a single tube. Viral DNA was detected in tench and roach samples up to 49 dpi, but in three-spined stickleback and stone maroko samples only up to 14 dpi. Transmission of KHV to naïve carp occurred after cohabitation. KHV DNA was detected in three fish species three months after the farm outbreak. We confirmed that grass and Prussian carp, tench, roach, and brown bullhead can transfer the virus to naïve common carp.

Histamine is one of the most important and toxic biogenic amines which may be present in food and may cause food poisoning in humans when contained at a high level. It is produced during bacterial decarboxylation of histidine in fish muscles. The aim of the study was to investigate the presence of histamine in fish and fish products available in Poland during 2014–2018. A total of 421 samples of raw (248), smoked (107), canned (50), and marinated fish (16) were analysed by high-performance liquid chromatography with diode array detection. Histamine was detected in 14.1% samples of raw fish, 29% of smoked fish, 22% of canned fish and 93.8% of marinated fish in concentrations ranging from 3.4 to 156.4 mg/kg. Content of this amine above 100 mg/kg was found in four samples: raw Atlantic salmon, smoked European sprat and two samples of marinated Atlantic herring. The study showed that fish and fish products on the Polish market generally meet the food safety criteria for histamine and are safe for consumers.