Elastomer tagging

This section explains how to tag threespine stickleback safely and effectively using elastomer.

You will need the following materials:

  • MS-222 (Tricaine Methane Sulfonate)
  • Sodium bicarbonate (baking soda)
  • Spatula
  • 1000 ml glass beaker
  • pH test kit
  • Holding tank and recovery tank
  • Air supply and air stone
  • Tagging kit including syringe and elastomer (e.g., Northwest Marine Technology)


  1. Fast fish for 12-24 hours prior to tagging. This will reduce fecal contamination and risk of regurgitation.
  2. Maintain adequate oxygenation via air stone in both holding and recovery tanks.
  3. Use water from the original source tank for transport, anesthetic, and recovery. If using another water source, closely duplicate the water quality parameters (e.g. temperature, pH, hardness, etc.).
  4. Maintain water temperature at the species’ normal optimum during both the anesthesia and recovery period.
  5. Make a desired volume of MS-222 solution in the beaker (concentration of 50-75mg/L) and buffer the solution to pH of 7-7.5 with sodium bicarbonate. Wear protective clothing, gloves, and goggles when handling MS-222 powder. If possible, work inside a fume hood to prepare solution.
  6. Anesthetize the fish in the MS-222 solution. Before tagging, make sure that the fish has slow respiration and heart rate, and is nonresponsive to stimuli. Observe the movement of the operculum as it opens and closes to assess rate. If respirations become extremely slow or stop, place fish in the anesthetic-free recovery water until respirations resume.
  7. To inject a tag, insert the syringe needle into the marking location (~1cm or less and just under the skin). Slowly withdraw the needle as the material is injected, so that a long narrow mark is created. It is important that the tag created is fully contained within the target tissue.
  8. Once tagged, place fish into recovery tank to recover.

Additional notes:

  • To begin, anesthetize a few fish and follow them through full recovery to ensure drug dosages and techniques are safe and provide sufficient anesthesia.
  • Dispose of MS-222 waste by flushing down the drain to a sanitary sewer with an excess of water.
  • If in a remote location where a sewer may not be readily available, further dilute the solution with water and dump wastes on land in a location away from water.
  • Do not discard MS-222 directly into surface water, storm water or catch basins.
  • MS-222 is a light sensitive chemical and should be stored in a dark container or in a cabinet/drawer.

RFID tagging

This section explains how to insert an RFID tag into a three-spined stickleback safely and effectively.

You will need the following materials:

  • Melafix (fish medication)
  • AmQuel or other water conditioner/detoxifier
  • Methylene blue and tea tree oil
  • MS-222 (Tricaine Methane Sulfonate)
  • Sodium bicarbonate (baking soda)
  • RFID tags, 8 mm (should be 30 in a packet).
  • MK-7 Implanter
  • Surgical blade
  • 1000 ml glass beaker
  • pH test kit


  1. Set up a 100-L aquarium that is completely cycled. Add about 4 mL Melafix, 2 mL of AmQuel, about half a cup of kiln-dried salt, and several drops of methylene blue and tea tree oil.
  2. Wear protective clothing, gloves, and goggles when handling MS-222 powder. If possible, work inside a fume hood to prepare solution. Mix a desired volume of MS-222 solution in the beaker at a concentration of solution of 0.3g/L. Buffer the solution to pH of 7-7.5 with sodium bicarbonate (will require about 1-2 times the amount of MS-222 added).
  3. Set up multiple containers of about 1 L to hold up to 3 fish immediate after tagging. Fill containers with dechlorinated water of room temperature (e.g., use the water we have in the tubs for water changes). Add a drop of tea tree oil.
  4. Wipe down work surface with 95% ethanol, and fill a small dish up with 95% ethanol. Put two clean paper towels on the work surface. Put a sharp pair of scissors, the needle portion of the MK-7, tweezers, and all tags to be placed in fish into the ethanol-filled dish. After several minutes, remove objects and place them on one paper towel to air dry.
  5. Place a single fish in the MS-222 solution until it reaches until fish reaches stage four of anesthesia (total loss of muscle tone and equlibrium; slow but regular opercular rate; loss of spinal reflexes). This will take about 1 minute for a stickleback of 5-6 cm. Stir the MS222 solution to check the fish’s equlibrium. The rate at which the pectoral fins beat is a good indication of muscle tone.
  6. While fish is being anesthetized, put on a clean pair of latex gloves. Use tweezers to load the glass RFID tag into the MK-7 implanter, being careful to get the tag all the way in.
  7. Gently remove the fish from the MS-222 solution using a large pair of tweezers and place on the second clean towel. Take the clean, air-dried scissors and make a small incision on the side of the fish, just under the lateral line and about a centimeter behind the pectoral fin. If the fish has lateral plates, the incision may need to be lower.
  8. Insert the loaded MK-7 implanter into the incision with the needle opening facing you, and with the point aimed toward the tail. Continue until 3/4 of the needle opening is within the incision. Keep the implanter as close to the dermis as possible as you insert. Then, rotate the implanter 180 degrees so that the needle opening is facing the fish. Push the plunger to insert the RFID tag. Once the tag is partially in the fish, pull out the implanter as you push the plunger further to minimize unnecessary penetration. Place tagged fish in the prepared 1-L container.
  9. Put scissors and tweezers back into the ethanol, as well as a fresh needle. Replace paper towels and latex gloves.
  10. Repeat steps 4-9 until all fish are tagged.
  11. Gently transfer all fish to the prepared 100-L aquarium, while wearing a fresh pair of gloves
  12. After 24 hours, add another dose of Melafix to the aquarium water. After 3 days, replace 25% of the water in the tank.
  13. Feed the newly tagged fish juvenile food for three days. Then switch to regular adult food.