Wet Specimen Resources
Tutorial
Supplies:
Formalin Replacement or Formalin
70% Isopropyl Alcohol or 70% Ethanol
Glass Jar (with tight fitting & sealing lid)
Syringe + Needle (for larger specimens)
RO/DI Water
PPE (Gloves, Goggles, Respirator)Step 1: Acquire a fresh or frozen specimen, defrost if needed. I like to place my frozen specimens in water to defrost, especially fish, to remove any detritus or slime prior to preserving.Step 2: Clean the specimen. This may not be needed in all situations, but when preserving aquatic animals, I like to rinse the specimen several times to remove any excess slime coat. However, be very gentle so you do not damage the specimen or remove scales (if present). Distilled water is ideal for cleaning because it doesn't contain any chemicals that may interact with your preservatives and is osmotically neutral.Step 3: Place the specimen in the initial preservative for fixation. You can use humectant fluid (will not technically "fix" your specimen but can work), ethanol (will fix smaller specimens less than 3" thick), a formalin replacement (not enough research to show efficacy), or formalin (very toxic, expensive to ship, and requires great care when working with, you must wear goggles and work in a well ventilated area, but is the best fixative in my opinion).10% buffered formalin is the industry standard for most wet specimen preparations, and I definitely recommend it - or a suitable formalin replacement for big specimens. Larger specimens must be injected thoroughly with the preservative. Any animal with a body part diameter of more than one inch should be injected. I use 16-20 gauge needles depending on the thickness of the specimen's skin/scales. Inject in every area that you can, the body cavity, musculature, and head being the most important as these areas are more prone to rotting. Inject until the specimen is somewhat bloated and the preservative begins to leak out. Be sure not to inject air as this can cause the specimen to float. If air is injected, you can unscrew the needle on your syringe and use it to aspirate where you think the air bubble is. If you do not have access to a needle, you can make small, deep holes or slits in the specimen with a scalpel to allow the preservative to saturate the entire specimen.Fixation is the most important step of fluid preservation. Putting a specimen directly into isopropyl alcohol or hand sanitizer does not stop deterioration of the specimen over time. Isopropyl works well as a preservative (killing bacteria and fungi that cause decomposition), but will not keep soft tissues stable, leading to a specimen falling apart eventually.
Fixation is the process of stabilizing proteins to make them stronger and not deteriorate/denature. It causes protein chemicals to bind (fix) to each other creating a strong matrix of cross-linked proteins.Step 4: Now it is time to wait. The specimen must soak in the initial preservative for 1-2 weeks if it's small, and up to a month if it is VERY large. Monitor your specimen as soaking time varies greatly depending on size/skin or hair texture, and color can be lost if soaked for too long. Inverting/swirling the jar gently every few days is also helpful and ensures that the preservative is making its way into the entire specimen. After a few days, the specimen will begin to stiffen, so it's important that you have it positioned how you want it to stay forever. When using alcohols, it is essential to note that they dry out the specimen which can cause shriveling. Monitor the specimen and slowly dilute the alcohol with distilled water if the concentration is too high and is causing a bad shrivel.Step 5: After soaking your specimen for a good while, it's time to switch out your initial preservative for 70% ethanol or isopropyl alcohol. Ethanol is a little better if you can get it because it causes less degradation over time. Drain your jar and dispose of fluid (formalin is hazardous and should be discarded carefully, look into your local laws on this).I usually rinse the specimen one more time in distilled water to remove any gunk and excess fluid that has accumulated. It is best to soak the specimen in distilled water for 24hr prior to switching to the holding fluid to ensure the preservative and holding fluid do not mix, I personally haven't had an issue skipping this step with smaller specimens, but I try to do this with any super delicate or large specimens.
Occasionally, shriveling will occur if placed directly into a higher percentage alcohol from a fixative or lower percentage alcohol. To reduce this, use diluted alcohol with RO/DI water (~30%) and slowly increase the concentration until you get to 70%.
Fill your jar with alcohol and wait another few weeks. The alcohol will likely become discolored and can be changed however many times you'd like before putting your specimen on display.Step 6: Once your specimen is done, you can leave it without changing the fluid again. The fluid may become discolored over time, but this is normal. Specimens used for scientific purposes usually never have their fluid changed as it is considered part of the specimen. However, if you don't like amber-colored fluid, you can swap your old alcohol out for fresh alcohol. If your lid isn't on tightly enough alcohol will evaporate, so monitor and refill if needed. It is always best to discard the old fluid completely and not "top-off" due to evaporation lowering the alcohol % over time creating osmotic imbalances.
Never leave your specimen in sunlight (this will bleach the specimen and increase degradation) or near a heat source (alcohol is highly flammable). Curved glass containers are also a fire hazard as they can create a magnifying effect, so be sure to keep those away from any strong light sources.
Tiktok Tutorals
General Wet Specimen TutorialPreserving a Large Specimen
Green Phantom Pleco Part 1
Green Phantom Pleco Part 2Preserving a Small Specimen
Betta Fish Part 1
Betta Fish Part 2
Sourcing Supplies
"Prefer" is a newer preservative on the market used as a formalin replacement. It is much safer to use than formalin, but I personally do not have experience with it. You can find it HEREFormalin is highly toxic and more expensive to ship, however if you prefer to use this chemical, you can purchase it HEREEthanol is a great option as a holding fluid and at higher concentrations, a fixative for small specimens. You may need to dilute down to 70% with RO/DI water for holding purposes. You can purchase it HERE70% isopropyl alcohol is very easy to find at most grocery and drug stores, but can be purchased in larger quantities HEREGlass jars can be found in many different places. I like to check out local thrift stores for more interesting pieces, but many grocery stores carry canning supplies as well. You can also buy many different sizes and shapes of glass jars online. I have found great 5-10ml jars on Amazon. I am sure many scientific supply companies have lots of bulk glassware as well.Syringes and needles can be purchased at local pharmacies, as well as scientific supply companies. I tend to reuuse needles until they are dull and have not had to purchase new ones in a very long time.
FAQ
Q: Can you preserve a specimen for me?
A: I would love to do this for people, but I am worried about dead animals getting lost in the mail and decaying. This may be a possibility in the future if I can figure out a reliable way to ship non-preserved specimens, but for now I recommend that you do it yourself. It is very inexpensive and easy to do.Q: Can I just put a specimen straight into a jar of alcohol?
A: Sometimes! I have had success preserving very small animals in just 70% isopropyl alcohol, especially small invertebrates like shrimp or crabs that consist of chitinous exoskeletons. I highly recommend preserving anything without an exoskeleton using the process above as fixation is the most important part of a long lasting wet specimen.Q: Can I use ____ to preserve a specimen?
A: There are many ways to preserve specimens, and many different chemicals you can use. I have shared what chemicals have worked for me, but this is not the only method or chemical combination that you can use.Q: Can you put a specimen in resin?
A: Yes, but it's not a simple task. Any specimen that contains moisture can cause resin not to cure fully. I have seen many decaying specimens suspended in resin as well. Plastination or mummifaction are the best ways to prepare specimens to fix in resin.