Scale
Calcein, which binds to calcified tissue, can be used to chemically mark the scales. Scale samples from marked fish can be taken non-lethally and observed under a microscope equipped with an ultraviolet light. A series of sequential mark/no-mark applications of the chemical can create a unique banding pattern on the scales groups.
Advantages:
- Inexpenisve
- Many fish can be easily marked
- Not intrusive
- Can mark small fish
Disadvantages:
- Field detection not possible
- Fish must be recaptured to acquire scale sample
- Specialized equipment and training to read marks