Comets Die Immediately

Question
Ok.  We have about a 25 gallon tank with 2 filters (one is a Whisper, the other a Bio Wheel) and were maintaining it pretty well.  Our last 2 goldfish lived for over 2 years, then all of a sudden they died within 2 weeks of each other.  Well we cleaned the tank and today I bought 2 comets and they died within 2 hours of being placed in the tank!  What could be causing this and what should I look for and do to prevent this from happening again?

Answer
Tonya,

Regular maintenance consists of filter maintenance and partial water chages of 20% every other week.  Failure to do the water changes will cause a buildup of ammonia, nitrites, and even nitrates.  Eventually any one of these, particularly ammonia and nitrites, will kill fish.  If you did not do the water changes the question is anwered.

You mention cleaning the tank prior to intoducing two new fish.  Do you mean that you emptied all of the old water and added all new water?  If so the same phenomenon takes place with ammonia and nitrites.  It is called the nitrogen cycle.  This is no doubt what killed your new fish unless there was some disease present that we know nothing about.

To prevent a reoccurrence of this set up your tank with everything running for about a month, adding one or two flakes of fish food every third day.  At the end of the month test for ammonia and nitrites using one of the cheap kits available for sale.  The water should test negative or 0ppm.  It is then safe for fish.  There are bio-accelerators avalilable that claim to speed up the process but I don't trust them.  I have talked to too many people who used them and lost their fish within days.  Good luck to you.

Michael J.