electricity has no effect on fish???

[VLDesign]

First of all if you are not using a grounding probe and/or a GFIC outlet then you run the risk of not only killing yourself but your fish as well.

Secondly, stray voltage in the tanks absolutly DOES affect the fish and can cause many problems including severe health issues.

Lastly, every single time I have heard about or personally experienced stray voltage it's either a bad heater or a RIO pump.

Want to avoid stray voltage? Use a grounding probe.
Want to avoid being killed by stray voltage? Use GFIC outlets.
Want to avoid equipment that can cause stray voltage? Don't buy RIO pumps.

 

[Bud8Fan]

Read this and decide for yourself before using a ground probe:

http://avdil.gtri.gatech.edu/RCM/RCM/Aquarium/GroundingProbes.html


I agree that GFCI's are a must have in this hobby though.

 

[Fish Eat Fish]

If you want to prevent this in the future either add a very small sump outside the tank or even on inside. A small tank just large enough to hold your heaters attached to a side of the tank at your water level so the main would overflow into it with a return pump would work just fine.