# A Review on Food Safety: The Case of _Citrobacter_ sp., Fish and Fish Products
## 1 Introduction  
Fish is defined as any food that can be extracted from oceanic or continental waters (fresh or brackish) intended for human or animal feeding, being a generic term that includes fish, crustaceans, mollusks, algae, etc. [1].  
Fish is considered a traditional and popular food in different regions around the world, and for certain countries, it constitutes the main contribution of protein of animal origin [2]. In addition, an increasing number of people choose fish as a healthy food option due not only to its source of protein of high biological value and digestibility, but also because of its content of polyunsaturated lipids, vitamins, and minerals [1; 2; 3].  
The quality of fish for consumption regularly refers to different conditions, including aesthetic appearance, freshness, nutritional value, degree of deterioration, and safety, where the absence of pathogenic bacteria, viruses, parasites, toxins, or various chemical compounds is involved [1; 2; 3].  
Fish and fish products are foods highly susceptible to contamination by various chemical hazards related to foodborne illnesses, including heavy metals, polychlorinated biphenyls, dioxins, insecticides, nitrosamines, antibiotics, hormones, biotoxins, biogenic amines (histamine), and biological hazards, such as parasites, viruses, and bacteria [2; 4; 5; 6]. They have also been related to numerous outbreaks of infections or poisoning in humans around the world, derived from consumption of microorganisms, in which bacteria are the most causative-related agents [2; 6; 7; 8].  
Microorganisms can inhabit and survive in many natural environments, being transferred to food and contaminating it at different stages of the food chain through soil, air, water, insects, animals, and humans [9]. Throughout the food chain, from capture or harvest to consumption, fish undergo various changes that alter their sensory, chemical, and microbiological features. During those various phases, a series of critical points, such as time, temperature, conditions, and hygiene practices in handling, among others, must be monitored because if they are not adequately controlled, they impact the sanitary quality of the product, transforming it into a high-risk food in terms of health intended for human consumption [10; 11]. In addition to this, the presence of hazards that put people's health and perception at risk has implications for the acceptability of fish for consumption, as well as the contribution of this food to human nutrition and health [12].  
_Citrobacter_ sp. has been related to agents of biological origin harmful to human and animal health. Therefore, the objective of this document is to provide a general informative perspective on the various contaminating hazards in fish, specifically those of biological origin such as _Citrobacter_ sp.; their impact on human and animal health, in addition to detection, prevention actions; and/or control of these hazards throughout the food chain, such as the implementation of good practices, the Hazard Analysis and Critical Control Points (HACCP) system, microbiological analysis, and sanitary regulation in fish and fish products. All of this in promotion of the safety of foods of aquatic origin destined for human consumption and the protection of public health.