Is it okay for a dog to eat a hermit crab?
There are several dozen foods that are perfectly fine for humans
but very bad for dogs/animals. Normal fish, If fed exclusively or
in high amounts, can result in a thiamine (a B vitamin) deficiency
leading to loss of appetite, seizures, and in severe cases, death.
Lobster is a shell fish; not quite the same but it's better not to
risk fido's life for a tasty treat. A tiny bit of anything now and
then (even chocolate or grapes) won't kill them depending on the
size of the animal but their food is based on their dietary needs
for a reason.