ricdl

I have just witnessed one of my danios swimming in a spiral without any self control. Now I can't find it, unfortunately I believe that it's dead, we are still looking. This is the second one to die this week The first one was right after I fed them some freeze dried blood worms and I figured he choked on one because I sometimes see them swimming around with a piece too big for the little pigs to eat, but this time was right after some flakes. I don't believe that I overfeed them because food never lasts very long (2 mins max). I did a water change last week and I just rechecked the levels.
ammonia 0
nitrite 0
nitrate 5-10
temp 76-78
Everybody else seems just fine including the remaining 3 danios, 6 serpaes, 4 lemon tetras, 3 angels, 6 harlequin rasboras, 1 cory , 1 pleco and a snail. The tank is 75 gallons and has been running trouble free since the end of June. Any help would be greatly appreciated. I wouldn't want this to continue every few days.
Also, in case this helps, the last 2 water changes I used Tetra AquaSafe to condition the water. Before I used an API product I can't remember the name of. Sorry about the long post, just worried about the fishies.

iloveengl

I'm sorry about your danios Is it possible that your angels paired and now they are being aggressive? I've used both type of water conditioners without problems.