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Soft Visible Implant Alphanumeric (VIalpha)
Product
Information
Fig. 1. Soft VIalpha tag in ambient light
Fig. 2. Soft VIalpha tag in UV light.
Advantages of soft VIalpha tags:
 | High retention in suitable tissue/species |
| Low capital costs |
| Tags detected visually and readable in live specimens |
| Minimal impact on survival, growth and behavior |
| Visibility is enhanced using blue LED light. |
| Made of flexible, biocompatible material that increases retention over the original VIalpha. |
Limitations of soft VIalpha tags:
| Unsuitable for very small fish and species without suitable tissue. |
| Tag readability may become occluded by pigmentation. |
| Slower than the original VIalpha to load and inject |
The new soft Visible Implant Alphanumeric tag (VIalpha) is a small bio-compatible tag, implanted beneath transparent tissue, and designed to identify individual specimens. In trials, at NM using rainbow trout, higher retention rates were achieved using the soft VIalpha tags versus the original VIalpha tags. The original VIalpha tags were made of a rigid non-fluorescent material. Because the soft VIalpha tags are relatively new, references on their use are not available. Our assumption is that the performance of the soft VIalpha, in terms of retention and visibility, will equal or exceed the documented results for the original VIalpha.The following text and references, which refer to the original VIalpha, can be applied to the soft VIalpha tags. Although many fishes have transparent tissue (adipose eyelids, fin membranes, clear boney tissue, etc.), tag retention varies by species. For example, the adipose eyelids of salmonids have generally proven to be suitable locations for these VIalpha tags, but implants into larger masses of similar appearing tissue in mullet (Mugulidae) have been rapidly shed, (further discussion of adipose eyelid tissue). Size of the tagged specimens is also important: shedding rates from adipose eyelids of salmonids less than 150 mm total length have been excessive while retention in larger fish often exceeds 90%.
Fig. 3. Soft VIalpha tag in adult chinook salmon.
Tagging sites in other body locations may also be used successfully. Various sites on the head appear to be particularly useful ( e.g., mandible in walleye Stizostedion vitreum [Larscheid 1995], and elsewhere on heads as reported by Buckley [1994]). Dorsal, anal, and adipose fins also provide potential targets (Tipping and Heinricher 1993, Oven and Blankenship 1993, Wenburg and George 1995). Body undulation combined with the relative stiffness of these tags appears to limit usefulness in more posterior locations. These tags are implanted with specially made syringe-like injectors, and are available in several colors (black letters on a red, orange, or yellow fluorescent background or the reverse), and in two sizes: standard - 1.0 x 2.5 mm, and large 1.5 x 3.5 mm.
LOADING THE INJECTOR
The injector needle is dipped in water or alcohol, if not already wet. The tags may be loaded into the injectors with either of two methods. For the first method, the white plastic cover is peeled back or removed and the strip of tags is held in the hand with the tag be loaded curved over the forefinger. At this point the backside of the tag is facing up; so the code on the tag is not visible. The open side of the needle point is turned down, aligned with the long axis of the tag. Slide the needle over the tag until the tag is entirely inside the injector (see figure 1).
For the second method, hold the tags with the clear plastic side up. The code on the tag will be visible with this method. Peel back the white plastics cover just enough to expose the tag to be loaded. The open side of the needle point is turned up, aligned with the long axis of the tag. Slide the needle under the tag until the tag is entirely inside the injector (see figure 2). Rocking the injector from side to side while loading tag will assist in easier loading.
