PIT tagging in fish and other animals

Photo credit: Troutlodge (USA)

Review: Abdel Rahman El Gamal (Founder of the website)

PIT tags (02) PIT tags (01)




The “PIT tags” stands for “Passive Integrated Transponders”. A PIT tag is biologically inert small glass-encapsulated electronic microchip that varies in size, usually between 10 and 14 millimeters long (12.5 mm is standard) and about 2 millimeters in diameter. Because the PIT is inert and has no internal battery, it remains dormant until its circuitry is activated by a close-range, electromagnetic field generated by the reader (scanner) where the unique alphanumeric code is received from the tag and displayed on the scanner as long as tags are within the range of scanners. The PIT is injected with a syringe. For best results, sharp needles are used.

The use of PIT tags in fish has been approved by USDA provided that the portion of the animal containing the implanted tag will not be used for human food.”   Therefore, the body cavity is the preferred location for all fish that will be released where fish may be caught and consumed.    In regard to farmed fish, the pelvic tagging location is preferred only if the tag is removed (confirmed with tag reader) along with the pelvic girdle when the fish is processed.

The pit tagging has several advantages over alternative to conventional marking methods. PIT tags can last through the life cycle of fish. In addition, data from the tag can be recovered without the need to anaesthetize, handle, restrain or kill the fish. This enables to identify and track individual fish throughout its life cycle whether in genetic selection programs or in their natural habitats such as in the homing of salmonids. In the latter situation, an antenna-type scanner is used which enables detecting the tagged fish which passes by an antenna’s electrical field.

Besides fish, PIT tags are also used for marking animals in field situations including mammals, birds, reptiles, amphibians, and invertebrates. The application of PIT is extended to zoos, private collections, and for identification for house pets. Moreover, CITES (Conference on International Trade in Endangered Species) has used PIT tags as a tool for monitoring illegal harvest of animals in international trade and verify that an animal is captive bred and not wild caught.



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