Yes.
"Dorado Fisch"
Yes, the dorado fish, or the mahi mahi, has lots of very small scales.
Fish and chips can be kosher if it`s made with kosher fish in a kosher kitchen. In fact, it was Portuguese Jews who introduced fried fish to England.
Kosher fish have fins and scales. I've attached a related link that provides a comprehensive list of kosher fish.
Fish and chips can be kosher so long as the fish used is a kosher species and the food is prepared in a kosher kitchen with all kosher ingredients.
The signs of a kosher fish are scales and fins. If the fish does not have either of these, then it is not a kosher fish. If it does, it is a kosher fish and one may eat it provided, of course, that it was prepared with kosher ingredients. According to "kashrut.com" (see link in related link section), the Grouper is indeed a kosher fish.
Yes opa is a kosher fish. Any fish that is born with scales and a dorsal fin is kosher. As long as it hasn't been touched by a non kosher knife
Basa fish, just like all other forms of catfish, is not kosher.
Sawfish, also know as Carpenter Shark, are a family of rays. These fish are not kosher as they do not meet the two requirements of kosher fish: movable fins and easily removed scales.
Rascasse fish is also known as Scorpionfish which is a kosher species. Please see the related link for a comprehensive list of kosher and non-kosher fish.
If it comes from kosher fish such as whitefish, yes. If it comes from non-kosher species such as sturgeon, then no.