Stumped

[salvatore]

Summary from previous posts:
Noticed ich in a few inhabitants and set up quarantine/hospital tank (20g, bio-wheel filter, airstone, pvc). Dont have a refractometer in the budget, so I bought copper (Cupramine) and a copper test kit.
Used water from the display, and have done 50% water changes every other day until the bio-wheel can catch up for filtration. Ammonia quickly showed zero and nitrite was as high as 0.5, but came down quickly as well.
Four fish in the qt: three damsels and magenta dottyback. Yesterday one damsel and the dottyback were both dead. Neither showed any signs of discomfort beforehand. I tested the water when I got home, and the nitrite was almost undetectable (the tests are difficult to read at best).
Salinity/SG is similar to the display, temp is 78-79f, and they're fed flake every other day.
The dottyback was the only one who showed signs of ich, and none of them had any visible symptoms when they were found dead. I understand most of ich is internal, but I dont want to just shrug my shoulders and say 'oh well they're dead, must've been ich'. Id really like to understand what happened and prevent it in the future.
What other factors should I be testing/looking for?
Semi-related: The test kits come with a card with colours to compare the test-tube results to. The colours on the cards are solid, but the results in the vial are almost always transparent. I know it wont be a solid colour in the vial, but should they be read as 'a slight tint indicates the tested-for level'? Does the tint intensity matter, or is it the presence of colour at all? This particular test is nitrite by Red Sea.
Thanks everyone.
I am your putty, mold me into the reefer I know I can be.

 

[beth]

You are supposed to place the test tube against a solid white surface, then read the results. Any level of nitrite is too much. Just because you got a slight pink color, doesn't mean that the nitrite level was so low that it would not effect fish health. The fact that a hobby test kit detects nitrite at all means its a problem. Any level of ammonia or nitrite is potentially lethal to fish.
I know that Terry and Ed will jump all over me, but I would’ve gone with the hypo even wo the refract. A good glass hydrometer will do. For perfection, the refract is what is required, however, with a quality hydrometer, you can do hypo....drop the SG a bit lower if you are worried about the precision of your instrument. We have had successes with hobbyists on this BB who use hydrometers and just dropping the SG to 1.008—if you’re concerned about accuracy.
Hospital tanks with multiple "patients" is stressful for fish. Removing fish from larger, marine simulated tanks, and placing them in what is essentially a “sterile” environment in close quarters with other fish is a stressful event. Copper treatment is stressful, period. Think of copper as you would chemotherapy. It is a metal which is toxic to organisms. It is used because it is the lesser of 2 evils: copper or parasite/chemo or cancer? That is why it is so important to avoid ever having to use a hospital to begin with by QTing.
BTW: Sick and healthy fish need much more nutritional options then what you are currently offering. Flaked diets just don't cut it with marine organisms. Go fresh food! It is cheaper and so much healthier. Your fish will love you and so will your tank [less pollution].

 

[beth]

Yes, you are right, Terry, 1.008 is too low if the testing mechanism is accurate. I should have clarified that if the hydrometer tends to measure SG on the low side, then drop the salinity a tad. A good glass hydrometer that you read in "still" water should give you good results.
Thanks!

 

[dvk]

Can anybody tell me what is ick looks like? I have a Koran Angel, and I noticed white "salty like" deposit cristals on its tail. Can anybody tell me what is it?

 

[salvatore]

I was feeding flake in the qt only because it seemed less messy than the fresh food. I have a diet of scallops and shrimp blended with carrot and broccoli pieces, and garlic mixed in. This gets frozen and fed to the display every other day. (When there's fish in it).
Thanks for everyone's help.