Before planned handling such as delousing, moving or sorting, it is important to carry out a risk assessment. Examination of damage to gill and heart tissue provides an insight into the tolerance of the fish and can affect a decision as to whether to postpone handling or perform it with additional caution. A fish whose heart appears as shown below has reduced cardiac capacity but will often display no signs of illness in a normal hatchery situation. During delousing or other stressful operations, such fish may die as a result of their impaired cardiac function. A quick risk assessment is more feasible now than it used to be, since, as in the case of real-time RT-PCR, the standard response time for histology is five days.