Feeding question on what you can and can't do

[djcentropyge1]

I've heard that many marine fish eat food like chopped squid or clam meat. Do fish need chopped squid to be specially designed for aquarium fish or can I use the type you can find in grocery stores?

[boilermaker1]

If its clean enough for you to eat... then the fish can eat it too.
Just freeze it first to kill anything bad that may be on it, since you're not going to be cooking it first.
A lot of people, myself included make fish food from the grocery store seafood counter.

[djcentropyge1]

What about preservatives? could any chemicals used in their storage (mostly canned food) harm a 55 gallon FOWLR+S (FOWLR+shrimp) tank or its inhabitants?