So- the main aquarium is fine. I worried last night because it had high ammonia after I did another water change (brought nitrates down from scary 80 to safe 30-40) but it appears the bio filter is handling it okay- this morning ammonia is near 0. My QT is another matter- I've got three cherry barb females in there. They look perky- not hiding, no clamped fins, only one is pale. I haven't got a good look at their skin condition yet (lights out and the room is dim). People tell me it's most likely a healing injury- from the fish sparring- old skin sloughing off. I still wonder about the filter intake, I'm going to get foam prefilter to put over it.
Now my issue is that the tapwater is high in ammonia- it seems the water company puts chloramine in, and I noticed this happened last year too, on 3/12. I didn't mention it here on the blog, but was asking on the fish forums, because I wanted to know if it was safe to dose extra with prime to nullify the ammonia.
On another note, I'm starting to think I should feed my fishes only 3-4 times per week. Some people do. Cold-blooded animals don't need fuel as often. And I saw this beautiful picture, browsing tank profiles, and my fish have never looked so pretty, so slim.