Fish tank woes

Question
Hi,

We have a 35 gallon tank, a submersable heater by tetra.  The filter is an outside filter attached to the tank.  We bought our first fish from Walmart and those fish actually lasted a month or so.  After that, we bought from a pet shop two different times and those fish are not lasting a week. I did do partial water changes of approx. 20-25%, every 3-4 weeks. The water was checked twice by the pet shop and they said that everything that they can check for was fine. I do use plain tap water but I use stress coat and stress zyme with every change. The fish hardly eat. I now have had the tank empty of fish for a while until I can figure out the problem. Please help!!!

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Followup To
Question -
Hi,

We started up a fish tank a few months ago.  We put tropical community fish in.  They lasted around a month.  Then we purchased six more fish.   We put in an algae disk (to feed the algae eater that we had bought) and within an hour, two fish died.  By the next morning, another two or three died.  The last fish died a week and a half later.   (It was a placo.)  We then purchased two more fish which were platties or mallies and they, too died soon after.  I did not notice any obvious disease on any of the fish.  But the last two to die were very inactive and did not look well.  We are scared to put in any more fish until we know what could be wrong and how to fix it.  What do you recommend?

Thanks in advance.

Answer -
Hi Daniel,
 Hmm... something is very wrong.  Fish shouldn't be dying like that.  

 So, here is what I suggest.  Please describe to me what equipment you have (ie., heater, filter, etc) and how you generally take care of the tank (i.e., water changes, etc).

Then we can figure out what is going on.

Also, are you buying the fish from a fish store or from some place like Walmart?

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>


Answer
Hi Daniel,
 It sounds like your fish are being poisoned by something.
 You aren't using any soap anywhere near the tank are you?  Soap (hand soap or dish soap) is extremely toxic to fish.
Or in the bucket that you use for water or something like that?

 Also, unless your water is really bad, you shouldn't need to add stress coat or stresszyme.  

  Is your water coming from a well or from a municipal water supply?  If the latter, it is possible that they are adding chloramine to your water.  If so, then you need to use Amquel to get rid of the chloramine, but only do that if they are adding chloramine.  If you call your water utility, they will tell you.  Be sure to get through to someone who actually knows, not someone who sort of thinks they know what is added.  (I have found the water guys very helpful on this matter).  

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>