Distinct growth patterns are produced in the natural environment and can be induced through a strictly controlled temperature regime. Natural marks are, by definition, carried by the fish, so no marking or additional handling is needed. Minimal effect on behaviour, growth, health and survival. Applicable to a large range of fish sizes. Cheap and fast to apply to a large number of fish.
Marks normally have a long duration.
Marking natural populations chemically requires retaining the fish for a period of time long enough to produce the marks. May be difficult to apply to natural populations in field studies. Pertaining to a change in number or in geometric relation to parts of an organism. If this definition is used Meristics can be used as heading for a large methodological category of methods used to identify or differentiate between genera, species groups, species, subspecies, populations or groups within species and individuals. The problem with this pooling of methods is that these methods are very unrelated by nature.