Does this sound weird to anyone else???

[XeniaGirl]

Here are the specs/inhabitants of my tank:

-12g NC, about 4 months old
-live rock, live sand
-all water specs are fine, temp between 80 and 82 degrees

-6 baby reef hermits
-3 small snails
-2 fighting conches
-1 sandsifter starfish
-xenia
-yellow polyps
-3 mushrooms
-zoas/button polyps
-fuzzy urchin

I had 3 fish in this tank for a little over a month, and in the past week and a half all three of them have died. In all cases, it was a very sudden thing. The weird thing is, everything else in the tank is fine and growing - I feed frozen brine shrimp 2x/week and liquid photoplankton 1x/week for the xenia.
The fish I had were a bicolor blenny and 2 false perculas (tank raised). No one fought, everyone was eating, etc.
I need to know what to look for (in water quality, other inhabitants, etc) to figure out what has been killing my fish! They didn't have chunks bitten out of them, nor ick, nor anything else that gives me a CLUE what happened.
I'm definitely not adding anything else to the tank until I figure out what's going on! Please help me to not feel like a murderer!!

[dobejazz]

Sorry for your loss
I have no clue I just lost my little flasher wrasse the same way

[YLChik]

I am so sorry for your loss!
I have also lost 2 fish in the last few weeks for no apparent reason also

Can ya post your tanks water parameters
gives us all ya can test for ... maybe that will help?!

[XeniaGirl]

I'll post up test results tomorrow AM - right now I'm about to close on a house so I just have a second...
wanted to add a few things...

1. Tank temp last few days has been 1-2 degrees higher than normal... closer to 83 or 84 degrees. Whenever I'm home I either turn off the lights or open the feeding lid/entire lid until the temp is closer to 81 or 82.

2. Two inhabitants I forgot - peppermint shrimp and emerald crab.

The only thing I can guess at this point is, either the fighting conch stabbed someone with his barb out of defense (although I've never seen them do that to any tank member for any reason) OR we have a mantis shrimp, although I think that's highly unlikely.
Would a slight increase in temperature kill 2 fish!?!?!?

[XeniaGirl]

FINALLY... here were tank specs from that fateful day...

(March 10)

Ammonia: between 0.00 and 0.25 (closer to 0 but I always write it down if it's not EXACT)
Nitrate: between 0.00 and 0.50
Nitrite: between 0.00 and 0.25
pH: 8.0

And just to clarify, this is how the tank qualities ALWAYS look in my tank, since December.
Also, the clowns were in my tank over a month (the blenny was there since the beginning so more like 4 months) and this all happened really suddenly.

Help.... !?!?!?!?!?!?!