angel fish stress virus

Question
Hi Ron,
I hope you can help me. Back in October I did a very stupid thing. The fishtank was looking so bad with algae so I moved all the fish (angels, siamese fighters, mollies, platys, neons, swordtails and soaking loach) to another smaller tank whilst I cleaned it out. 3 hours later I returned the fish to the original tank.
Fish were fine for 3 days and then the angels started swimming at an angle and sitting in the top corners with their heads pointing upwards. They stopped eating and were covered in a slime.
The other fish seemed fine. I have since learned that the angels have stress virus. I increased the water temp from 28 to 32 and after 2 weeks they started eating but not in the normal manner. Instead of swimming to the food they opened their mouths at the water surface and if any food floated into their mouths then that was what they ate.
All the other 15 fish have died between October and now   one day fine the next dead. All I have remaining is the 2 sick angels. Approx 5 days ago one of them lost the ability to swim and was lying on its side on the gravel just flapping its fins. I thought perhaps it was the end stage of the stress virus and expected to find him dead the next day. He is still alive and lying on its side flapping its fins. He obviously hasnt eaten anything for days and I dont know if there is anything I can do as I cannot find any literature that mentions this. Please can you help?
My tank is 260 litres with 2 filters and all water readings are excellent.
Regards
Lynne

Answer
Hi Lynne,
  That is all very peculiar.  I have never heard of "stress virus".  There are lots of terms out there on the net that really don't mean anything.  All fish get stressed when their environment changes and just like with people, if there are viruses present (as there always are), then the viruses do better when an individual is stressed and their immune system is compromised.  So getting "stress virus" is not really the problem.  The problem is why were they so stressed?  Or more importantly, why are they still stressed after several months?

  When you maintain a tank, the key is to do regular weekly partial water changes.  You need to change 25% of the water once a week, every week.  That alone will keep your fish healthy moreso than anything else.  Changing more than that tends to kill off all the good bacteria as well as the bad bacteria which makes it difficult for the tank to maintain any sort of biological balance.  Then a fish will die. The dead fish puts a ton of nitrogen into the water which causes more problems, more fish die, etc.  So, the key is that as soon as a fish dies, do a 25% water change.   Have you done any water changes since October?

Also, NEVER use any soap or cleaning detergents anywhere near a fish tank.

-- Ron
  rcoleman@cichlidresearch.com
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