Yes, they do have both fins and scales.
Anchovies are not birds, so they don't have feathers. Anchovies are not mammals, so they don't have fur. Ahchovies are fish, so they do have fins.
Yes all tuna have fins and scales
Yes all species of Tuna have both scales and fins.
All fish are kosher except for those that do not have both fins and scales, such as lampreys. Whales and dolphins - which are of course mammals and not fish - are treif (not kosher); as are molluscs and crustaceans such as mussels, whelks, prawns and lobsters. So yes, anchovies are a kosher species of fish.
Most. There are very few fish that have no scales and all fish have fins.
No it does not have scales, and yes, it has fins
There are many classes of fish which do not have scales nor fins. The Agnatha has neither fins nor scales; the Condrichthye, including sharkes, rays and skeats have fins but no scales; the Ostichthyes, of which several families have members with the common name, mackerel, with both scales and fins. The King Mackerel, S. cavalla, has very tiny scales and fins.
Tilapia fish has fins and scales like any other fish. The tilapis fins and scales are less difficult to remove.
Yes, all fish with fins and scales are kosher.
Pacu are a type of piranha. They do have scales, like most fish, as well as fins.
Black codfish do have scales, which are generally very small. Possibly due to the size and color of the scales, it may seem that the black cod does not have scales.