The present study was carried out for detection and identification of Enterobacteriaceae in retailed and farm fish as Tilapia nilotica and Mugil cephalus and in Kafr El Shiekh Governorate. The obtained results were revealed that 47 Enterobacteriaceae strains were isolated from 50 Tilapia niloticus fish samples with a percentage of 94% (25 from retailed fish and 22 from farm fish). On the other side 46 isolates of Enterobacteriaceae strains were isolated from 50 Mugil cephalus with a percentage of 92% (22 from retailed fish and 24 from farm fish). The most dominants isolated strains were Citrobacter spp., Enteriobacter spp., Klebsiella spp., Proteus spp., and Serratia spp. This together with the highly pathogenic Enterobacteriaceae including Salmonella spp. and E. coli.

Evaluation of some quality indices was carried out to determine the nutritional value of the most cultured freshwater fishes and to estimate the tolerance of these items to remain in good condition against damage. Quality indices were evaluated in 90 samples from three different fish species (Mugil cephalus, Oreochromis niloticus and Clarias gariepinus) 30 of each were collected at different times from different farms in Kafr Elshiekh Governorate, Egypt. Results of pH, total volatile nitrogen (TVN) "mg N /100g", trimethylamine (TMA)" mg /100g", thiobarbituric acid (TBA)" mg/kg" and peroxide value (PV)" meqO2/kg" were 6.

Histamine fish poisoning (HFP) is caused by consuming a bacterially contaminated fish that are capable of producing histamine. Histamine may cause food intolerance and allergic reaction. The aim of this study is to investigate the occurrence and level of histamine in fish that are commonly consumed in Kafr Elshiekh Governorate. Accurately, 90 samples from three different species of fish represented by Mugil cephalus (M. cephalus), Oreochromis niloticus (O. niloticus) and Clarias gariepinus (C. gariepinus) (30 of each) were collected at different times from different farms in KafrElshiekh Governorate and examined for determination of their histamine levels "mg%" using Enzyme-Linked Immunosorbent Assay (ELISA). Histamine was detected in all fish samples with mean values as following 9.76 ± 0.12 in M. cephalus, 13.32 ± 0.17 in O. niloticus and 21.05 ± 0.26 in C. gariepinus with acceptability of 82.22 % according to EOS (2005).