We have a collection of around 70 species specimens from 20 families; all from Vembanad Lake, Kerala, India. We would like to know what all are the effective long term preservation techniques, either using Isopropyl alcohol or something else; except Ethanol (due to availability issues in Kerala). We would like to display these wet specimens too, since there are no collections of this kind available in the vicinity.
Dear Anu, We also changed our fish collection from formalin to alcohol some years ago. If the fish were fixed in formalin first, there no problem with conservation in alcohol. Use glass jar only as plastic one deteriorate after years. Just make sure to use very good lid on top of your jar to prevent as much as possible evaporation. It will occur anyway so you need to have a well ventilated room for health and safety. A special care should also be given to fire risk analysis and prevention. In case you do not want to put your specimens anymore in formalin and you want to fix them directly in alcohol make sure you have enough volume because alcohol is not very for fixing tissues. You will need a large amount of alcohol compare to the volume needed with formalin. I hope this can help you.
Dear Mario, thank-you for the response. Infact the issue lies with the availability of ethanol in Kerala, India. Our head office does have license (to be used in Bangalore, India) but cannot be used in a field office. That's the reason we have planned to use isopropyl alcohol. But, its effect of fish specimens in making the latter brittle in course of time made me a bit concerned of taking any step further. Different literatures have mentioned use of glycerol and CaCO3 inorder to counter this effect of isopropyl alcohol, though a standard amount to be used or a method to caliberate the same was not mentioned.
Dear Anu,
Some museum specimens that I have studied were ca. 30 years fixed in isopropyl alcohol and were in excellent shape (no glycerol or CaCO3 was added) . I cleared and stained some of those specimens with excellent results. All were marine specimens. In contrast, all freshwater specimens from different museums, used in my studied, were fixed in ethanol 70%. To add 3-5 cc of glycerol to the isopropyl alcohol will "soft" the effect of the isopropyl alcohol in the same way that you can do with ethanol 70-100%. But... if you use larger quantities it may have some effect on the translucence of the skin.
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Dear Gloria,
Thank-you for sharing your experience. I'm planning to go forth with 70% isopropyl alcohol as the solution. Will note changes periodically if possible.
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