Some species do and some don't
Tuna are all marine (saltwater) and they are predatory, so yes, tuna eat saltwater fish. They can only eat saltwater fishe because they do not live in freshwater.
There are all sorts of different fish in the oceans and seas, and there are many different diets associated with them. There is no one food that ALL saltwater fish will eat.
yes
no
dont you mean saltwater fish?
they eat them
If the fish can find the eggs and/or babies they will eat them.
No
both i think
Yes they do. Striped Bass and other Saltwater species love Bloodworms. Some people say that Nightcrawlers or even earthworms are something that Saltwater fish eat. I have never tried that though. I know those worms work great for Freshwater fish. A lot of Saltwater species like Blood and Sandworms a lot.
no saltwtr fish eat saltwtr food tropical fish eat tropical food fresh watr fish eat fresh watr food
Fish in aquariums eat fish food found in any pet or fish store. Fish in the wild mostly eat smaller fish and small particles in the water. Some types of fish living in aquariums also eat smaller fish. Often, fish will eat their own babies so aquarium owners know they must move babies to a smaller fish bowl or tank to protect the babies from the adults.