I realize their natural waters move very slowly but I have my 90 malawi with excellent filtration (About 800-1000 GPH) They don't seem too stressed but I wonder if they might like less water movement? Theres also a 3" bubble disk I could dispose of if need be.
the only thing I think that would be a problem is if you breed them. Sometimes the strong current can wash away the milt from the male. If the fish don't seemed stressed I wouldnt worry. I had a problem awhile back with my fronts not holding, I switched over to sand (gravel is a egg killer) and lowered my flow somewhat when I see a tube down and I am hoping that will help. My last batch, 2 females spit them after 2 days but I think that was stress because I got some new lights.
Im not trying to spawn them but it happens lol id rather it didn't to be honest but oh well(My bichir is happy when they get fry going thats for sure). I unplugged the air pump to see if there is more activity. I figure since fish really dont like to swim through the bubbles it may utilize a little extra space or something like that.
They should be fine.....that's a lot of filtration going on in your tank!
As to water flow, they should be fine and actually enjoy the current. In my 75 TruVu long, I have an AC901 coupled to a sponge filter and the guys love to swim against current!