According to the professional

This is what Michaela Gerstner, where the fish comes from, tells me: Hello Johan Meffert,
Today we send the fish.
At this size 25 kg/m3 is o.k.. Later, when the fish is big (2,5 kg/piece) 100 kg/m3 is possible.
One Waller has the weight of about 21 gramm.
So you can keep at the moment 1200 in m3