Fish can be kept in conditions like this but I think it's cruel...
I saw those water monitoring devices where fish sits in a tiny stall (size of the fish), water pumps through the stall and fishes breathing and hard beat are being monitored. This way possible to detect presence of contaminants, toxins etc. Fish does not dye there. They do not eat for month as well. They do not die either. Are they happy? No... Same idea.