I drew out about 1/3 of the water in the big 36G this weekend to do plant maintenance (remove dead leaves, rearrange a bit, add some new ones). I gave the girls a treat of Freeze dried mysis when I was all done.
Next day one of them was at the top with SBD symptoms. I pulled her out, put her in a QT tank with warm water and stresscoat, and fed her a soaked FD daphnia later. She looks much improved today, doesn't appear to be fighting her own bouyancy...but I'm wondering if the water change, new plants, or the mysis treat might be things known to cause SBD? (Or all three combined?) I'll put her back in the big tank tomorrow if she continues to be fine, but I'd like to avoid a repeat!