all my fish died

Question
I have a 135 gallon fish only tank and all my fish died. I fed them yesterday and all was well and today i came home all my fish were dead and my water all of a sudden smells like chlorine or bleach maybe both the only fish that survived are my snowflake and ribbon eels can you help please  

Answer
Hi Miguel. For you to come home and have all your fish dead with a small of chlorine or bleach sounds to me like sabotage! I can't think of any natural process that would go on in your tank to give you this kind of odor coming from your tank. Typically when certain biological processes go on in your tank that end in the results you encountered there would be a smell of rotten eggs. This would happen from the formation of sulfur compounds accumulating in your tank in areas of very low water flow like in a deep sand bed that is not adequately turned over. When this happens there will be an overwhelming smell or sometimes no smell at all and the symptoms are death. There is also an electrical smell that can come from using a ozonizer. This will have a definite electrical smell and means you are using too much ozone. This will often result in a wipe out of the entire system as well. As for a chlorine smell I would say that even if you are using chlorinated water the concentration of chlorine would be too low to have such an abrupt outcome of death and usually no smell is detected. I would look at who could have possibly had access to your tank and see if anyone could have inadvertently or purposely gotten some in there. A full 100% partial water change should be performed as well as using fresh activated carbon somewhere in the system to rid your tank of this toxic element. Luckily chlorine evaporates quickly and is not absorbed by your porous materials in your tank. So once cleared up there should be no further leaching into your tank. Your tank will have to cycle all over again and it may take several months to become re-established and stabilized.