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Putting Fish to Sleep – 5 things you must do

I hope this is not something you ever have to do at home.  In a commercial farm knocking the fish out is fairly common however we use the APVMA approved chemical Aqui-S.  Handling fish in any way is stressful to both you and your fish and at times I am not sure which is worse.  I am always edgy when doing this.  When you do handle them it is important to be prepared and ready to go as quickly as you can. We have included in this post a very rushed video of the process of almost putting our Jade Perch to sleep to check on a lesion I noticed when feeding.  I did not particularly want to post it as it may stress some people to watch it but you may learn something from it. You might ask how would I get an infection.  There is a multitude of reasons you may get an infection in any given system.  Fish just injuring themselves on fittings in the tank can turn nasty or any other given environmental conditions.  The simple answer is we did not clean the solids filter for 4 weeks, running a denitrifying trail and the accumulated organics combined with upper temperature limits has most certainly stressed the fish and often a secondary bacterial infection soon follows. Some might say the system is over stocked or not in a “state of balance”.  I think 37 x 700 gram fish or 26 kg in 3000 liters to be quite a light load.  If you are struggling with that, perhaps a revisit to your design might be in order.  All water quality parameters outside of the high temperature and elevated Total Suspended Solids, were fine.  It is very important to check these before doing anything to the fish and correct as needed. Following heavy salt treatment and moving of the fish to a clean tank, they all recovered and back on the feed within the hour and bacterial infection stopped in its tracks and all the fish are healthy and growing.  No losses is a good thing. We used clove oil to anesthetise the fish (not euthanize) before we handled them.  Here is a document that provides some doses for common anaesthetic agents in fish. In that document is suggests to mix the clove oil with ethanol.  This is very effective but not many will have ready access to it so I simple add it to water and shake it up vigorously to emulsify the oil and water.  You can pick up ethanol from a chemist in small amounts.  I have read using Vodka or some other alcohol, but I would leave that alone, the water works just fine. I mix 10ml in a 300ml jar and shake it for a few minutes than add a little bit at a time, wait a few minutes, then add more and wait.  Repeat until the fish start to tip on their side.  This can be quite unnerving if you have not seen all your fish upside-down before, so take a deep breath! 5 things you must do Aerate the water heavily Add small amounts of the mixed clove oil at a time Have the same tank water ready for them to go into Avoid longer than 10 minutes exposure Be very prepared and move fast (do not dally) This is not something to play around with but you can “dull or dumb down” the fish to reduce their awareness in times of severe stress.  Such as handling and even environmental issues.  But not something you want to be doing on a regular basis. Regards Paul…

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