Can you tell me if you have ever noticed very tiny, almost minute,
bubbles that stick to the sides of the tank. Super saturated gases can
form. This often occurs when water goes over a dam. The fish get
nitrogen gas bubble disease and die off possibly weeks later. I believe
they stop flow of blood to small vesels. They take a long time to
The bubbles seem to stick to the sides and can be moved a goodly amount
before breaking loose to the surface.
This condition could have occurred many weeks prior to fish die off.
Cloudy eyes can be a result as the optic nerve requires a lot of
oxygen. These bubbles are similar to those formed when Seven Up is
poured, only much smaller.
Chris is correct, this most often happens on the intake side of a pump.
Also when cold water is allowed to warm after being released from
presure in a pipe.
I have noticed liver and kidney damage, bulging of both eyes ( best
viewed from above ), scales standing outwardly, an overall bloating,
and sometimes hemorraging seen at the surface. And sometimes the gills
curl a little outwardly as fish try to get more oxygen. I cannot say
these are all caused by the gases. Their presence can exasberate any
existing problem, and/or weaken a fish for new maladies.
I am in no way an expert, but have worked with zebras and other
tropicals since 1957. I feel more fish are killed by this, than not
taking chlorine out of water.
George Streisinger would be amazed at how much is being done with the
AB strain of Zebra Danio.