smell in the water

Question
my fish are slowly getting sick. I have had three die already. I have checked the water and it is fine but it has aawful smell to it. I have sharks and eels. Is there anything I can do to save the rest of them and do you know what would make the water smell so bad

Answer
Dear Kathy,
Above all, please immediately do a water change.
Anytime your water has a bad smell or your fish seem to be dying for no apparent reason, always do a 30-50% water change right away. Remember to always make the replacement water equal in temperature to that of your aquarium and always dechlorinate it with a good water conditioner.

~I would repeat these water changes everyday until the smell is gone and insure to vacumm the gravel with an aquarium siphon.

There are a few reasons why your aquarium could smell. Most of them are serious problems you must investigate to save the lives of your beloved fish. Firstly, what is the smell like I guess I should ask. Is it like rotten eggs? if so, then Anerobic bacteria may be present in your gravel bed where the gravel has become so clogged with debri, oxygenated water cannot reach and aerobic (beneficial bacteria) cannot thrive and anerobic sets in and releases toxic gases which are extremely dangerous to your fish. *You must do massive daily water changes and vacumm the gravel extremely well everytime. Hopefully with these actions, your fish should survive.

Other things that can make your water smell bad could be extremely varied, either something that got into the aquarium from outside sources or an object in the actual tank leaching harmful substances.

Dangerous things like Anerobic bacterial activity in poorly vacummed gravel or undercleaned filters can be one of the biggest causes of a bad smell in the water.

*Now another thing might be Ammonia. Especially in new aquariums. But if your test results showed ZERO ammonia. Then this couldn't be your problem.

I really hope this helps!
Only my very best wishes and Best of luck!
Karen~