Vitamins are organic compounds essential for growth, health condition and protecting the body against many diseases (Vitamin-deficiency symptoms) in the most organisms including fish. Vitamin C has been to be necessary for the formation of tooth, bone, anhatching larvae were used to investigate the optimal treatment conditions for fish masculinity procedure by either immersion in 17a-methyl testosterone or infeeds. The results of these experiments could be summarized as :The results concluded that Tilapia (Oreochromois niloticus) which fed on50 mg vit C/kg diet recorded the best values of growth performance andhealth condition, in comparison with those of the other experimentalgroups. On the other hand, these results were noticed many clinicalThe occurrence of Staphylococcus species and Enterobacteriaceae in Atherina species (freshwater and marine):A total of 300 Atherina fish (210 freshwater and 90 marine) were examined for the presence of Staphylococcus species and Enterobacteriacea in their surface swabs and muscles. Results revealed that S. aureus were isolated from 194 surface swabs out of 300 Experiment-IIOccurrence of Staphylococcus species and Enterobacteriacea in water used for preparation of Atherina fish for selling:A total of 130 water samples used for preparation of fish for selling were collected from the same places from which Atherina fish were collected. The prevalence of S. aureus was 53.1% (69 out of130). Meanwhile, the coagulase negative Staphylococcus spp. Experiment-IIIOccurrence of Staphylococcus species and Enterobacteriaceae in hand swabs of Atherina fish handlers:- Out of 100 hand swabs examined, S. aureus and coagulase negative Staphylococcus spp. were isolated respectively from 73% and 50% of the examined samples. Enterobacteriaceae isolated from hand swabs were E. coli (5%), P. vulgaris (8%), P. mirabilis (5%),Experiment- IVSerogrouping of E.coli isolated from Atherina species, water used for preparation of Atherina spp for selling, and their handlers:-Ten representative biochemically identified E. coli isolates (4 from Atherina fish, 3 from water used for preparation of fish for selling, and 3 from hand swabs of fish handlers) were subjected to serodiagnosis. The 4 isolates from Atherina fish were idenExperiment-VEffectiveness of freezing, salting, and commercial vinegar (5% acetic acid) on the survivability of S. aureus and Enterobacteriaceae in fresh water Atherina fish:A) Effect of freezing.The effect of freezing on the survival of Staphylococcus spp and Enterobacteriaceae was studied. Atherina fish were examined before and after freezing. The isolated bacterial species from surface swabs of the unfrozen Atherina fish were P. vulgaris, P. miB) Effect of saltingThe effect of salting on the survival of Enterobacteriaceae in freshwater Atherina fish was studied. Atherina fish was examined before and after salting at (25%, 50%, and 75% NaCl solution). The isolated bacteria species from the surface swabs of 10 examiC- Effect of commercial vinegar (5% acetic acid)The effect of commercial vinegar (5% acetic acid) on the survival of Staphylococcus spp and Enterobacteriaceae was studied. Atherina fish were examined before and after vinegar treatment. The isolated bacterial species from surface swabs and muscle sample