Malawian Cichlids - gasping at the top of the tank

Question
Hi.  I have a 70 gal tank and have various (~ 20) Malawian Cichlids. A couple of days ago I was cleaning the poo out of the bottom of the tank and replaced the water with tap water (around a couple gallons) without adding the chlorine neutraliser.  Yesterday one of the Socolofi died and the other one is in problems. All the other cichlids are at the top of the tank gasping from the top of the water.  I have since (last night) added the anti chlorine and bacteria.  I have also added the white spot medicine as they all seem to have little spots in their fins.  The fish are still having problems and I am not sure whether I should change the majority of the water (40 galls) or will that be too traumatic in their current condition? Please can you advise?

Answer
Hi Sohail,
  It is possible that there was a water problem, but I would look to other things.  Is the air system working on the tank?

  Is the filter working?

  When you added water, was it much colder than the existing water -- that can create big problems.  

  From what you have said, I would do a large water change (about 50%) and see what happens.

  Also, keep an eye on the fish to see if it isn't that one of the fish is becoming very aggressive and is attacking the other fish.

-- Ron
  rcoleman@cichlidresearch.com
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