Fast droping Nitrate levels killing fish?

I have a small 5 gal tank, i use to have 4 mollies 2 died in the first week and a half the other 2 lived for a few more months up until this morning when i found 1 dead on the bottom of the tank. In the last few days both fish have been eating less and laying on the bottom most of the time ( i think to one that is still alive might have ich but im not 100% sure).

Since the last week and a half i have been working on lowering the nitrate level in about 10 days it went from 140 to about 90 could this major drop killed the fish??

 

Hi,
I'm assuming this is a freshwater tank but never-the-less I have a feeling you didn't let it cycle properly and the high nitrate killed the fish. More than likely you still had high nitrite and amonia....my guess without knowing other water parameters.

 

ya it is a frestwater tank and when i got the fish i didnt know anything about cycling or water chemistry i thought u filled the tank with water ,put to the fish in, fed them ,and cleaned the filter...Was i wrong but i know alot more about everything now

 

nitrates in a freshwater are more lethal then saltwater. You want to get them down before replacing any fish. You also want to test for nitrite and ammonia because these are very lethal as well.

Do you do water changes, clean out the filter media, and vacuum the gravel?
You want to do water changes monthly and clean out the media every two weeks.

Do some research on GreenX, I used this for nitrate problems in my cichlid tank but do some reading on it first because I haven't used it in a long time.

 

Nitrates are not really a killer of live stock!!! As stated above nitrites and ammonia are probably the culprits!!!!
Sorry to haer about your loss!
Unfortunately, livebearers are not that hardy IMO!

 

I do about a 40% water change every week, clean the filter evry 2-4weeks but i dont vacuum the gravel. the nitrite is at .5 right now
and i plan on geting the tank well under control before adding new fish

Thanks for your help

 

i just put in some "ammonia clear" tablets made by jungle

 

How are you cleaning the filters? The filters should be cleaned in the tank water that you remove during a water change. If you clean the filters with fresh tap water you are killing all of the beneficial bacteria that has built up on the filter media.

 

when i say i clean the filter i mean i replace the screen inside the filter i have an aqua-tech 5-15 gallon power filter

 

and i rinse the Bio-fiber cartridge as need also
when i said screen above i ment cartridge