I have to disagree thereFour reedfish would need a tank somewhere around the 200 litre size.
I have kept 4 reedfish quite happily in a 100G for over a year
the most important thing when keeping reedfish is the foot print of the tank.
At least 48 inches long and 15 inches wide would be the min,
however if you increase the width you can decrease the length slightly
so a 39 x 19 would be just as good (as I kept mine in such a tank before I got the 100G)
height doesn't matter as long as you don't exceed 32 inches
a 200l tank fits those measurements, 48x15x17 = 200l.