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Instructions for NMT's Visible Implant Alpha Tags (PDF 1.03MB)

Instructions for Using Soft VI Alpha Tags (PDF 46K) APG02

Tagging Reptiles and Amphibians (PDF 60K) APE05

Fluorescing Visible Implant Elastomer and Visible Implant Alpha Tags (PDF 43K)


Visable Implant Alpha Tags (VI Alpha)

The VI Alpha Tag is a small, fluorescent tag with an alphanumeric code designed to identify individual animals. VI Alpha Tags are implanted internally but remain externally visible for easy recovery.
Our current VI Alpha Tags were introduced in 2010 and are:



VI Alpha 002 

VI Alpha Tags are now available in two sizes: standard (1.2 mm x 2.7 mm), shown in yellow, and large (2 mm x 5 mm), shown in orange. The larger tags are easier to read than the standard tags, and are suitable for larger animals.





VI Alpha Tags in ambient lightLarge tags have black lettering on a fluorescent orange background, while standard tags are available with black lettering on a fluorescent orange, red, yellow or green background. Each color has 2,500 different codes.

Tag readability and detection can be enhanced by fluorescing the tags with the VI Light. The tags on the left are shown in ambient light, while those on the right are illuminated with the VI Light.


VI Alpha Tags are easy to loadVI Alpha Tags are easy to load. Slide the tag into the needle, and snap it off.





VI Alpha Injector

Along with the tags, we redesigned the VI Alpha Tag Injector. The new needle is much sharper and can be inexpensively replaced. Most reptiles and amphibians can now be tagged directly with the injector, rather than having to make an initial cut in the skin to insert the injector.  

VI Alpha Injector.JPG

Two versions of the injector body are available. Injectors labeled “V2.0” can be used with either the large or standard tags (though you will have to insert the corresponding needle). Injectors without the “V2.0” can be used only with the standard tags.

V2.0 Body.jpg

For more information, or to place an order for the VI Alpha Tags, please contact NMT Biology
(biology@nmt.us; 360-596-9400).

Using VI Alpha Tags  

VI Alpha Tags are easiest to read when they are placed under clear or translucent tissue. In some cases, the tags can be placed under pigmented tissue where they are not visible in ambient light, but can be seen when they are fluoresced with the VI Light. This tends to be more effective if the tissue is evenly pigmented rather than mottled.  

Many fish have transparent tissue (adipose eyelids, fin membranes, clear boney tissue, etc.), but tag retention varies by body location and species. For example, the adipose eyelids of salmonids have generally proven to be suitable for VI Alpha tags, but implants into similar tissue in mullet (Mugulidae) have been rapidly shed. Buckmeier and Irwin (2000) [Abstract] found that 100% of VI Alpha Tags implanted in the dorsal fin of channel catfish Ictalurus punctatus were shed. However, researchers with the Iowa Department of Natural Resources developed a successful method of implanting VI Alpha tags into the tongue of flathead catfish (Pylodictis olivaris). Please see our Spring 2000 newsletter(PDF 45K) for further details. The size of the tagged animal is also important. Shedding rates from adipose eyelids of salmonids less than 150 mm total length can be excessive while retention in larger fish often exceeds 90%. More on Adipose Eyelid Tissue here.

VI Alpha Tags are widely used for individual identification of amphibians as an alternative to toe clipping. Tag retention tends to be nearly 100%, although the visibility of the tags varies based on the pigmentation of the overlying skin.



VI Alpha Tags are sold in increments of 100 tags. All 100 tags must be the same color, and will have consecutive coding.





100 - 900  



1,000 -  4,900



5,000 +



VI Alpha Starter Kit
100 VI Alpha tags Injector
Replacement Needle and Shim
VI Light (7 LED)


VI Alpha Injector


VI Light (7 LED)


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