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It's hard to classify the oldest one as the more primitive and the newest species as the the most advanced. The reason is that there is no absolute best fish configuration, it evolve in tandem with the environment and interaction with other fish.
As a general rule, you can include characteristic that are common to all fishes to be fairly ancient trait. That said, many trait that were the majority at one point are now less common. For example, this mean old species, large bulky scale (sturgeon,Coelacanth) , lack of Gas bladder, lack of jaw. but we can't call a shark a primitive fish even if it have no gas bladder (he even have a sixth sense we don't have, electrical field detection). Some very primitive looking fish because they have no predator can stay that way but still evolve special apparatus, like those using a light in deep ocean to attract prey.
Also, there is the tiktaalik. That even if very old, was the prototype of land animal.
Some old trait come back over different evolution path. For example walking fish.
Some fish that might look totally ordinary can do amazing thing. For example the flying fish. Those can do 50 to 400 meter flight in the air. It don't use a very advanced new organ, just different configuration of fins length and muscle.
Personally i think the more advanced on almost all point and also the more adaptable is the cat fish. those have sub species that can walk on land and some in Africa can live months under sand and mud until the rain season come back. They also have an incredible sense of smell.