Loosing fish HELP

[Jason McK]

I haven't been able to come up with a reason. But it started about 2 weeks ago when I lost 1 Chromis and a Bicoloured Blenny, Now I seem to be loosing a fish a day. This morning I lost my Watanabe Angel, Yesterday was another Chromis, before that was a christmas wrasse, before that leaopard wrasse. I've tested everything and my Ammonia is 0.01, Nitrite 0.0 Nitrate 0.0. I have seen some invert deaths but for the most parts they are OK. I did set up a frag tank recently. Also the bodies show no sign of attack, the evening before they fed well and acted normally. no new fish have been introduced for months

Any suggestions would be great.

Jason