We have just built our first small scale aquaponics system in an IBC container. We have decided to go for catfish, as we have read they are the easiest to grow and are perfect for beginners. We have placed four 1.5kg catfish in the bottom part of the IBC container (650 liters). After 3 days we found them dead. What could have been the issue? The water was clean, well oxidized – we have a pump 3500L/h, certified organic food from a specialized shop, appropriate temperature. Were they too big for the container? Apparently, catfish can be stock in high densities, so that shouldn’t have been the issue either. Any ideas please?