this is alt text

Why is There an Electric Current in Your Fish Tank?

5 min read

We get a lot of questions about aquariums here but sometimes an unusual question pops up that most people wouldn’t think of because they have never experienced it.

Our question for today is, why is there an electrical current in my fish tank?…

There is an electrical current in your fish tank because a piece of your aquarium equipment like your heater, pump, etc. has electrical components that are supposed to be waterproof but are being exposed to the water current because the equipment is too old or faulty.

Quite shocking of course(no pun intended) but that is actually how some people realize there is an electrical current in their fish tank – by getting shocked haha…

Okay not funny if it happens to you so let’s dive in (not into your aquarium) and learn about this issue.

When To Suspect An Electrical Current In Your Fish Tank

The most obvious way to tell of course is when you stick your hand in the tank and feel it but your fish will also let you know when there is an electrical current in your tank.

Even before you first put your fish in the tank you should check for an electric current in your tank, especially if you are using aquarium equipment from a new or unproven manufacturer just because it was cheaper.

When your fish start acting erratically, then you know that something is probably wrong.

If you wait too long, they may get what is called hole-in-the-head or lateral-line-erosion disease. You willl recognize this disease by pits on the face and head of your fish.

You might as well check your tank with a voltage meter right away to eliminate an electric current as the problem.

If there is an electrical current and you don’t realize it, you may end up treating your fish for sickness, changing the water, replacing faulty equipment that isn’t bad, etc, and still have the same problem if you don’t get rid of the electrical current.

How To Check Your Aquarium Water With A Voltage Meter

You can usually borrow a voltage meter if you don’t have one or you can buy one for $25 or under

You want to use the setting: 120 AC Voltage.

The black probe is the grounding probe, so you need to stick it in the ground hole of a socket or extension cord.


Put the tip of the red probe, which is the positive tip, into the aquarium.

Any voltage or digital reading indicates that you have an electrical current.

How To Pin-Point Where The Electrical Current is Coming From

First things first, you need to disconnect one piece of aquarium equipment at a time and then retest the water with your voltage meter. This means anything plugged or even battery-powered like heaters, pumps, chillers, and even lights.

If you want to go all out, you can remove all of your aquarium equipment and check it for cracks, worn or damaged parts, or even chewed pieces of equipment.

You especially want to check all of your electrical cords where they attach to the equipment and the actual electrical plug.

If it is your aquarium heater, you want to make sure there is no water in the heater in addition to checking it for cracks.

How To Get Rid Of The Electric Current In Your Aquarium

Obviously, you want to remove the defective piece of equipment when you find it but here are some other things you can do:

Plug all of the aquarium equipment into GFCI outlets.

GFCIOut PetAquariums Why is There an Electric Current in Your Fish Tank?

GFCI stands for ground fault circuit interrupter. If your aquarium equipment is plugged into these and the circuit breaker keeps going off then you know you probably have a faulty piece of aquarium equipment.

Inspect all of your aquarium equipment at least once a month during one of your water changes.

You can try to minimize any electrical contact between your equipment and the water by:

  • Keeping all parts of the electrical cords out of the water.
  • Use external equipment like hang-on-the-back filters.
  • Keep the cord and temperature control for the heater out of the water.

Make sure you always have a drip loop in your power cords. This is where the cord goes down from the aquarium and touches the floor before going back up to the electrical outlet. This is to ensure that any water on the cord runs down to the floor rather than into the electrical outlet.

You can get low-voltage equipment if the equipment is submersible.

How To Use A Ground Probe In Your Aquarium

You can install a ground probe in your aquarium according to the manufacturer’s instructions.

If too much electrical current is flowing through your aquarium, it will trip the ground probe and flow into it instead so you and your fish don’t get shocked.

This is just a safety feature though and shouldn’t be used to solve an electrical current issue rather than solving it.

Stray Voltage Versus Stray Current

When you measure voltage, you are just measuring whether or not electricity is present.

You can have some voltage in your aquarium that isn’t harmful, ie, you usually won’t feel it with your hand in the tank or it will barely register on the multimeter.

Sometimes a little voltage is generated just from magnets inside a pump in your aquarium.

When you measure current you are measuring whether electricity is actually traveling in a path through something.

The current is much more dangerous when you touch the water because it is already flowing through your aquarium and will flow through you.


Electrical current in your fish tank is no joke!

Make sure you check for this regularly and replace any submerged electrical equipment regularly so it doesn’t have a chance to go bad.

Remember, if you can, get non-submersible equipment, so it doesn’t have a chance to touch the water.

Always have a drip loop with your cords so any water that touches them travels to the ground and not the socket.

Get a GFCI circuit breaker and a ground probe if possible for safety.


Written by:

Pet Aquariums

Have you any questions?