Delayed Mortality Syndrome or DMS is associated with losses that occur in recently transported fish (Noga, 2000. Stoskopf, 1993). Fish suffering from DMS experience osmotic dysfunction and inhibited immune system response. Transport stress is diagnosed clinically by a decrease in plasma osmolarity in freshwater fish or an increase in osmolarity in saltwater species (Carmicheal et. al, 1984. Robertson et. al, 1988). Severely stressed fish can lose up to 10% of their body weight in 9 to 49 hours. This weight loss is attributed to osmotic dysfunction leading to dehydration (Sleet & Weber, 1982). These fish are susceptible to opportunistic pathogens, especially bacteria that take advantage of stress-weakened hosts (Mazeaud et. al, 1977). Infections caused by DMS usually become apparent within the first week after shipping. However, the critical period is longer extending to several weeks.
Steps to treat or reduce acute stress and DMS (Noga, 2000).
•Prophylactic treatment with antibiotics
•Frequent, small water changes.
•Reduce stress during transport and other manipulations such as netting.
