PIT Tags for Wildlife and Animal Identification
Passive Integrated Transponder tags give each fish or wildlife study animal a unique, permanent ID that reads through water and tissue. UID makes ISO FDX-B PIT tags in two implant sizes, plus the injectors, cartridges, and field readers needed to place the tag and retrieve the ID.
- FDX-B · Low Frequency
- ISO 11784/11785
- ICAR certified
An Implantable ID that Lasts the Life of the Animal
A PIT tag is a passive transponder about the size of a grain of rice, sealed in biocompatible glass. Implanted under the skin or in the body cavity, it carries a unique 128-bit identifier that never repeats and reads at low frequency through water and tissue where higher frequencies are absorbed.
There's no battery and no maintenance. UID's tags are built to last the life of the animal. The 2.1 x 12 mm format is the standard size; the 1.4 x 8.5 mm format allows implantation in species too small for the standard microchip.
From Tag Selection to Recorded Read
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Pick the size
Choose 2.1 x 12 mm for the read-range and retention of a standard tag, or 1.4 x 8.5 mm for juvenile fish, small amphibians, and other species where a 12 mm tag isn't an option.
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Load the injector
Tags ship in injection-ready cartridges. Drop a cartridge into a single-shot needle for sterile clinical work, or load a Multi PIT Tag Injector for high-throughput field tagging.
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Implant
Inject subcutaneously or intraperitoneally per your study protocol. The biocompatible glass capsule keeps the implant profile low; the passive design means no batteries and no maintenance.
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Read
Pair the tags with a UID reader — handheld for recapture sampling, antenna-mounted for in-stream or in-burrow detection. Every read returns the same unique ID, every time, for the life of the animal.
The PIT Tag Family
Tags, injectors, cartridges, and accessories.
- Standard PIT Tag
FDX PIT Tag 2.1 x 12 mm
- ISO 11784/11785
- ICAR Certified
The standard PIT tag at 2.1 x 12 mm for standard sized animals.
View 2.1 x 12 mm Tag -
Small Species PIT TagFDX PIT Tag 1.4 x 8.5 mm
- ISO 11784/11785
- Small Species
Smaller PIT tag at 1.4 x 8.5 mm for juvenile fish, amphibians, and other small-bodied species.
View 1.4 x 8.5 mm Tag -
Complete KitPIT Tagging Kit
- Complete Bundle
- Species-Paired
Tags, injector, cartridges, and a handheld reader. The fastest way to start a PIT-tagging study.
View the kit -
Multi-Tag InjectorUMTI-10 Multi PIT Tag Injector
- 10 per Cartridge
- 2.1 x 12 mm Only
Cartridge-fed injector that places 10 tags in sequence, allowing you to implant several animals before reloading.
View UMTI-10 -
Refill CartridgeEmpty PIT Tag Cartridge
- Up to 10 Tags
- Box of 10
Reusable cartridge for self-loading up to ten 2.1 x 12 mm FDX-B PIT tags into the UMTI-10 Multi PIT Tag Injector.
View UMTI-CAR Cartridge -
Injector NeedlePIT Tag Injector Needle
- Triple-Ground Tip
- Box of 10
Replaceable triple-ground injection needle for the Multi PIT Tag Injector. Box of 10.
View needle
Common Questions
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Is a PIT tag an animal identification microchip?
Yes. A PIT tag is a passive implantable RFID transponder with an internal microchip and a permanent identification number. PIT tag is the term most often used in fisheries and wildlife; pet and laboratory-animal workflows more often call the same technology family a microchip or implantable transponder.
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Which tag size should I use — 2.1 x 12 mm or 1.4 x 8.5 mm?
Use the 2.1 x 12 mm tag whenever the animal can carry it — it has a longer read range and is the standard across most fisheries and wildlife protocols. Step down to 1.4 x 8.5 mm when body mass or implant site won't accommodate a 12 mm tag: juvenile salmonids, small-bodied amphibians, shrews, lizards. The smaller tag has less volume and a shorter read range, so plan antenna placement accordingly.
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Are UID tags ISO compliant?
Yes. UID's FDX-B tags operate at 134.2 kHz and conform to ISO 11784 and 11785 — the standards that govern animal RFID identification. They're ICAR certified, and they read on any ISO-compliant FDX-B field reader.
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How long does a PIT tag last?
The tags are passive, with no battery, and are built to last the life of the animal. The ID is hard-coded and never repeats.
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What's the difference between FDX-B and HDX?
FDX-B (full duplex) and HDX (half duplex) are the two ISO-compliant low-frequency PIT tag protocols. UID's tags are FDX-B, which is the more common standard in fisheries and most wildlife studies. HDX is sometimes preferred for in-stream antenna arrays where longer read range matters more than tag size. If your study has already specified a protocol from existing infrastructure, match it; otherwise FDX-B is the default.
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Do the tags ship sterile?
It depends on the format. Tags loaded in single-shot injector needles ship sterile and individually packaged — appropriate for clinical or surgical implantation. Tags in pre-loaded cartridges for the Multi PIT Tag Injector ship in non-sterile form, which is the right call for high-throughput field tagging where sterility isn't the limiting factor. Confirm packaging with us when you order.
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Which reader should I use with these tags?
The URH-2 is the handheld reader for recapture and point-of-capture scanning at close range. The URH-300HP reads FDX-B and HDX at 6–8" and is rated IP67. It pairs with the URH-PLEX antenna for underwater scanning. See the full lineup on readers, injectors, and accessories.
Looking to Integrate RFID into Your Study?
Call us. We can help you choose the right tags, injectors, and readers for your program.