Someone tell me about a Mantis or Pistol

I have lost 5 fish in my Pico Tank. All were healthy one day and dead the next. Except one. He jumped. I hear a snap, or click now and then. What are the symptoms? Do they kill, eat, poison, or what. None have ever disappeared. I have heard some things about this, but never experienced it.

 

You could very well have either. However, if either one were the reason for the death, you wouldn't have ever found a body. In a pico, it could be temperature swings, pH swings, high nitrates.

 

Nitrates are a little high, they are at 20. They have never killed any of my others. This last one to go was a Chromis that I had since Christmas. Very very active fish. Was perfectly fine the night before when I fed him. Next morning he was almost dead. 15 min later, gone. I immediatly tested the water. 0 amm 0 nitrites 20 nitrates. I have had much higher readings in my 150 with no deaths....I'm lost. BTW. All of my snails (3) are just fine.

 

If you give a chromis a dirty look, they'll die. They are just not a very hardy species.

 

I guess you are right about that. I just did not want a Damsel. Any suggestions??