It is a really tough call, fish can die because of old age, disease, sensitivity to dissolved chemicals we never test for etc... I think the thing to look for again is simply consistancy. If you keep a log of water changes, tests, fish added, fish deaths you may see a long term pattern. Radio shack sells a Intel Microscope, if someone is really concerned with premature death of fish I would encourage them to do a disection, set up slides and look for a cause of death. Do a google search on marine fish diseases and you will have lots of material to compare your slides too.
Myself, if a fish dies in my tank I have to assume I didn't meet its needs, or it died of old age.... If all my fish start to die, I assume there is a disease of some sort.
|