i would have to say no.
while there are a number of "freshwater" fish that are capable of going between salt and freshwater, i don't think that cyprinids are one of them.
If the referenced "black fin sharks" are Hexanematichthys (formerly Arius) seemanni, aka "Columbian shark cats" or "white-tipped shark cats", then the answer is yes:
This species is a member of the only SW catfish family, Ariidae. It occurs in FW and brackishwater as juveniles and requires heavily brackish water to SW as an adult.
None of the other species are even remotely related. As mentioned, they are FW cyprinids and shouldn't even be kept in brackish conditions.