The fish that have been placed in the greenhouse with the last workshop unfortunately all died of a fungal disease. Last wednesday 28th may the first fish got sick and showed some cottony-white growth. On friday five of the seven fish were already dead and two fish where very sick. The two fish got a salt bath and got a bit better but still didn't survive the weekend.
The fungus turned out to be Winter saprolegniosis or winter kill syndrome which occurs in cold water. The water in the greenhouse is much colder because the system is outside and therefore the fungus had the opportunity to spread and kill the fish. RIP friends..