Black Moors

Question
I have a 55 gallon, that is rather new so we are still cycling.  When we set it up a couple weeks ago I added Bio Spira, Seachem Prime, Seachem Stability, StressZyme, Tetra's Easy Balance and added Marineland's Diamond Ammo Chips to the filter cartridges, which was a 60 gallon hang on.  I got uneasy about using a 60 gallon filter for a 55 gallon tank with 3 messy goldfish so I switched to a 110 gallon Aqua Clear hang on filter.  I also have a 10 inch bubble wall for extra aeration.  Because of the Bio Spira my ammonia has always been 0 and my nitrites and nitrates began to register immediately.  I had only been doing 25% water changes every third day because my quality levels have been good.  I transferred my two small orandas over to the 55 gallon.  They have been healthy and happy.  I waited a little bit for the nitrites to fall to zero, and when they did and I added another goldfish, a black moor.  He has been fine and seemingly happy for 3 days, but then I noticed he was hanging out in one corner of the tank (not floating or sitting on the bottom but just suspended) with his fins clamped.  I tested the water, 72 temp, 7.8 pH, 0 ammonia, 0.25 nitrites, 7.5 nitrates.  We do have soft water, but it is potassium sofetened and I have learned to do the water changes at the spicket for the hard water.  So we did a 25% water change, it was due anyway, for the nitrite level.  He refused to eat and he has been in that corner hovering for two days.  My others are fine.  Then I noticed has lost a lot of his black color and his body looks very gold.  He is starting to get one teeny tiny spot of slime coat build up (not fungus, I do know the difference with that) on his head.  I have continued to do 20-25% partial water changes daily for the nitrites and added AmQuel Plus for two days now.  Yesterday I added a half dose of Quick Cure just in case it's ich starting and I've had good success with using that as a preventive in the past.  Something I did must have worked because he ate today and his fins aren't clamped but he is not as active as the others.  My orandas are very busy, swimming, picking at ornaments and the gravel.  This guy just hovers in the corner all day even though he appears to look a little better today.  Is he sick?  I have not had good experiences with black moors in the past.  One I had bought (prior to this tank set up, died within 30 days, 2 more died within 12 hours and this is my fourth one that I did buy from an aquarium specialty shop, a different place than the first three).  If he's sick how should I treat it and is there anything different that I can do for the nitrite levels?  Thanks!

Answer
Hi April,
I think the best thing you can do for your aquarium, the black moor and the nitrite level is to give them some time. And do those water changes consistently everyday until things get better. You may be better off doing more like a 50% water change to have a bigger impact on the nitrites. Your tank just needs time to establish and settle. Black moors do tend to be more sensitive than other goldfish. I'm not sure why. :(

But all you can do is try your best. There's nothing better for fish than clean water. Keep using the Amquel which should help a lot also.

Best wishes and I really hope your little guy pulls through!
Karen~