Shock Tank for Fish Removal

[Asagi]

Hi All, this question may seem like blasphemy, but I'm curious. I've seen that a number of national parks will apply an electrical current to streams to temporarily stun the inhabitants. This is done to keep tabs on the fish populations, or some such ecological whatever. The fish seem to be stunned for a moment, but then are released back once counted/tagged with no real lasting affect. I have a fairly large mixed reef (150 gallons) with about 5 fish that i would like to remove. Have had this gang for about 8 years, and an honestly looking to get rid of all fish (except for the skunks). Fish traps are not really working, plus I grow a bit bored waiting to pull the trigger cable. Anyway, if you guys have any thoughts, other than fish abuse posts, please let me know your thoughts. Thanks All!

 

[Peach02]

While I don’t know enough about how to reccomend this I do know that getting electricity run through you is very dangerous

while I won’t mention the ethics side, Its safe to say that to little current may not do anything and too much will kill everything in the tank, likely with a very small margin of error.
plus the people doing It in rivers have a lot more than 150 gallons of wiggle room

 

[Whisperer]

I haven't done this but thought about it in the past. Do not use an electrical outlet, use a car battery instead. Two prongs at each end of the tank each connected to a conducting wires. I will have another person to help hold the prongs while you quickly complete the current on the battery terminals (that's how I visualized the process). This way you control the shock the fish receive. I take it draining the tank is not an option because of the corals and labor involved. I'm not sure how the inverts will fare but I feel shrimp will not take it lightly and may not wake up after the shock.

 

[saltyhog]

Never heard of doing this in salt water, only fresh water. Salt water is a lot more conductive. I would be afraid of not just killing the fish but everything else.

 

[Greg P]

This thread is shocking

 

[Jesterrace]

Never heard of doing this in salt water, only fresh water. Salt water is a lot more conductive. I would be afraid of not just killing the fish but everything else.

Agreed. The much higher mineral content in saltwater would be like a super conductor. Definitely not something I would risk. As for being impatient with the trap door, simply remove it and feed exclusively from the trap over the next few days. Once the desired fish becomes accustomed to eating from the trap, then replace the door and trap when it enters. I've used this method with 100% success, it just takes a bit of patience but it's much better than waiting the whole time with the string.

 

[Asagi]

Agreed. The much higher mineral content in saltwater would be like a super conductor. Definitely not something I would risk. As for being impatient with the trap door, simply remove it and feed exclusively from the trap over the next few days. Once the desired fish becomes accustomed to eating from the trap, then replace the door and trap when it enters. I've used this method with 100% success, it just takes a bit of patience but it's much better than waiting the whole time with the string.

Maybe I’ll just get my spear gun out?

 

[Asagi]

I haven't done this but thought about it in the past. Do not use an electrical outlet, use a car battery instead. Two prongs at each end of the tank each connected to a conducting wires. I will have another person to help hold the prongs while you quickly complete the current on the battery terminals (that's how I visualized the process). This way you control the shock the fish receive. I take it draining the tank is not an option because of the corals and labor involved. I'm not sure how the inverts will fare but I feel shrimp will not take it lightly and may not wake up after the shock.

Now this is a man of action!

 

[acan-man]

The term you are looking for is electro-fishing. I have done quite a bit of it for my research on trout (7 years). It will not work in salt water. As mentioned above, the mineral content makes for much higher conductivity. This has a different affect than mentioned above however. The current will actually travel around the fish, not through it. It works in freshwater due to the low conductivity of the water compared to the higher conductivity of the fish. If the conditions are correct this will temporarily stun the fish. If they are not correct you can either simply annoy the fish, or kill it. The machines we use for sampling are multiple thousand dollars and preformed under specific permits. Side note, can't say much about shrimp, but crayfish bounce back very quickly from the shock.

for some light pleasure reading on the subject

http://www.uvm.edu/rsenr/wfb232/Electrofishing%20manual.pdf

 

[Katrina71]

Wow. Remind me not to take too long in the tub or pool around here.

 

[jd371]

Have you thought about using a fishing hook and line to get them out? Get the right size hook for the fish you'll be hooking and crush the barb. I've seen this done before and it works. I bought small fishing hooks and was getting ready to hook a Falco Hawkfish that suddenly went rogue and hated most of his tank mates but it eventually settled down so I no longer needed to remove it.

 

[mtfish]

I did not read the manual Acan-man cited, but we use a 5 kw generator with stainless steel probes for our fish work in fresh water. Two kill switches, ear protection, rubber gloves and boots and fiberglass poles with nets. And as stated, will not work in salt water. We use gill nets for that, but not so great for catch and release! I would use a fish trap or small barb-less hooks to get the fish out of the tank.

 

[GoldeneyeRet]

I will have another person to help hold the prongs

Lol good thinking. I'll ask my wife! Really honey, you wont feel a thing...

 

[Asagi]

Have you thought about using a fishing hook and line to get them out? Get the right size hook for the fish you'll be hooking and crush the barb. I've seen this done before and it works. I bought small fishing hooks and was getting ready to hook a Falco Hawkfish that suddenly went rogue and hated most of his tank mates but it eventually settled down so I no longer needed to remove it.

ok, will try this. stay tuned.

 

[jd371]

If the fish are aggressive eaters you shouldn't have a problem, it's the timid ones that might take a while to hook. Good luck!

 

[Asagi]

If the fish are aggressive eaters you shouldn't have a problem, it's the timid ones that might take a while to hook. Good luck!

The 9” fox face is gonna be a real treat to take off the hook

 

[Super Fly]

Does your tank have a lid? if so read on... I recently had difficulty trying to catch a fish using trap w food & nori and after countless days/hours I accidenlty figured out that the fish were not entering trap b/c the tank screen lid was off! Have no idea how the fishes can tell this but its true. I reduced feeding for 2 days and after wasting many days & hrs sitting by the tank holding the trap line I was resigned to giving up. I left trap in tank w food and put back the screen lid. 10 mins later I happened to walk by the tank and wouldn't u know it ALL the fish were going bonkers entering the trap and eating! In less than 10 mins I caught my fish...