Red scooter blenny poisoned?

[cheapreefer]

I had to move some rock around last night in one of my newer tanks (4 mo's old). Under the rocks was a countless no. of pods and worms that my scooter gulped up. After that he didn't seem to move much, he normaly "scoots" all over the tank. This morning I found him dead

. He was my first fish in the tank and seemed very healthy till last night. Could something he ate have poisoned him? If so, what? Thanks.

 

[Ben1]

I doubt he was poisoned. Most likey you stirred up the sandbed, if you have one, too much when moving the rocks and caused an ammonia spike, which was very toxic.

What else is in this tank?