Clove oil is a good alternative as a fish anaesthetic. It is e.g. relatively inexpensive and is generally regarded as safe for the user and for the fish. However it is light sensitive and recovery period after the anaesthesia may be long, especially in cold (<5°C) water. Sensitivity to clove oil may also vary between species, so it is advisable to test it before using it in larger extent.
clove oil is not FDA approved in
Clove oil can be obtained easily from health food stores, eg. Luontaisprisma in Jyväskylä, tel. 630782, open 10.30-19.00. Unfortunately they sell clove oil only in 10 ml bottles, which cost about 5€ each. If you need more than one bottle be sure to place the order before going there. For bigger amounts it can be useful to get it from a porcelain painting shop, e.g. http://www.andersmeder.fi/ , where it seems to be much cheaper (15 € for 100 ml).
How to use clove oil:
1) prepare a solution of clove oil with ethanol (94%): 9 parts ethanol + 1 part clove oli. Keep this solution in a dark bottle, preferably also in the dark. Clove oil must be mixed with alcohol before use because it is insoluble in cold (<15°C) water.
2) use this solution to anaesthize your fish. If you do not have earlier experience with clove oil with the specific species, I would advise to start with the concentration of 40 mg/l. In practice this means that you add 2 ml of the solution into 5 l of water. You should be able to immobilize the fish within about 3 minutes.