And just like us, sometimes illnesses reign. We go to a doctor, get some antibiotics and all is well. Our fish don't get that. Not just because we're farming organically, but because our systems would die if we eradicate our bacterial colonies.
Stress
Humans mostly talk about stress in relation to work or social relations. That's our environment, it's what we think is important. For fish, their environment is the water they live in. In fact, they are the water they live in, with some membranes to keep them together. Just like we get the flu when we're overwrought, fishes get sick when something's wrong in their environment. Stress is the main cause of death, whatever illness takes the blame.
One prominent quality of water is that its properties change very slowly. Because fish have evolved in water, they've adapted to slow changes. If something suddenly happens, they get a shot of adrenaline and try to get away, something they can't do in our tanks.
It's not for nothing we're measuring our water all the time. All the values we measure make a difference to the ecosystem. Other things are important as well, like light, sound and temperature. Too much or not enough of something might cause stress, cause immune systems to fail and cause illnesses and death.
Sick
So, it's the farmer's job to keep values within acceptable parameters. Unfortunately, we did something wrong, because our catfish show the strangest symptoms and die.
We could spend a lot of time trying to determine what kind of illness is killing them, but instead, we'd better focus on getting the parameters right so they can take care of it themselves.
There is one thing we can do, so we did it: we took the sickest fish out of the tank and put them in a separate quarantine tank with salt water. Because of the salt, the fish need less energy to regulate osmosis, which they can use to beat the pathogens. It's like a sanatorium for them.
Better
Less fish are dying since the quarantine, but now and then we still find a dead one floating around. It's a sad sight. It's also frustrating that every change of a water value has to be done very slowly, not to stress the fish. We sincerely hope things get better soon.
So get out of your stressful environment, breath clean forest air and you will be able to beat the flu yourself!
Just like our fish. We hope...