Yeah.
Your whispers bio foam should be able to handle your four with no problem. If you get many more you'll need to up grade on your filter (bio load). I wouldn't add too many anyway, not much of a foot print(bottom area) in a 29. I run two whisper 60s on my 55gal mbuna tank with 8 cichlids(5"-2"), 1 cae(5"), 1 red tail shark(4") and 1 silver tip shark(8"). I kinda need to get rid of the silver tip, he's too big for the tank and will only get bigger.
this is a old picture
