Had trouble

[hrdneglcry]

I cannot say everything here as it would take 3 pages. I returned home a trip. One Niger Trigger was dead the other is blind. Inhave had them for years and grown them from small. The salt and the ammonia are fine. Its a 180 g with a 3 chamber 120g sump. My two groupers, my damsel and my Black Durgeon Trigger are fine. I have chaeto in the sump. I can't figure it out. I don't expect everyone to know. I have been in the hobby since 2005z I started with 900 gallons of predator reef tanks after coverting my freshwater hatchery. But my one Niger was dead the other is blind. I have no nitrate/nitrite tester.
I did use blue gravel from the pet store and mixed a small amount with the aragonite. I have had two eels that I had for years in this tank all of a sudden fall ill and die. They became where they could not breath. I test for ammonia and salinity.
I have asked before if these blue rocks could be the problem.
I changed 60 gallons today but the damage is done. The fish were fed daily when I was gone.

 

[EnterName]

Can you name the specific product of blue gravel you have used?

It sounds more like an infection issue though. Heavy breathing and blindness could be flukes if I remember correctly, but I don't know much about fish diseases and someone else has to make a proper diagnosis. Images of the fish will certainly help.