Although I am very much in favour of fish diversity, I would say that we should wait with the introduction of african catfish till spring. We might consider the introduction of another indigenous species like carp this winter.
I am getting around 500 fishes, that will be shared eaqually between our system and another guy that is also interested in breeding european catfish. I think 250 for us is plenty, don't you? I could buy more if you think we can house them..Have not found a delivery address in Germany yet, but that will be solved