Many people say no because there isnt much current in the rift lakes.Of Malawi,Tanganyika,and Victoria I would say victoria is the only one whos water movement is enough to call a real "current",although malawi does get pretty turbulent during storms.Tanginyika is very calm almost all year round.
The thing is I have my tank being filtered at about 16X an hour and that makes some fair current but they dont mind.
My theory for this is that maybe there isnt much current in the lakes but theres also a whole lot more space,so they can swim around and stay fit.It would make sense to me to make up for the lack of space by providing them with a current they can swim against.
hope theres an answer to your question in there somwhere....however vague,LOL