Behind the scenes at the Fish Facility

The challenges and joys of killifish care

The African turquoise killifish (Nothobranchius furzeri) is a small fish found in ponds and puddles across Zimbabwe and Mozambique. As this fish lives in pools that dry out during the dry season, the embryo stops developing when it is still protected by a thick membrane called corion. Once the rain falls, the fish develop quickly, reaching sexual maturity in about a month and a half. In captivity, turquoise killifish can live from six months up to a year, making them the shortest-lived vertebrates bred for research purposes. As they age they undergo significant changes in appearance, behaviour and many biological processes. As such, few other animals have recently captured the attention and imagination of ageing researchers as much as this small fish.

Christina Paetzold and Mattias Werres work as animal caretakers in the Max Planck Institute for Biology of Ageing, where they ensure the wellbeing of the killifish and advise and assist researchers in their work with this organism.

A contribution by Mihaela Mihaljevic and Jonas Goergens

How did you become animal caretakers?

Christina:  I’m actually not an animal caretaker by training, but an animal medical assistant. I completed my training at a veterinary practice However, I wanted to focus my work more on the research aspect and as such, I came to the institute.

Mattias: Initially, I didn’t want to become an animal caretaker. I started studying social pedagogy but quickly lost interest in that. Since I’ve always been a fan of animals, I thought being an animal caretaker might be a good alternative for me. At first my goal was also to go into a veterinarian clinic, but research turned out to be both more interesting and better paid. My training took place at the Scientific Poultry Farm Rommerskirchen and involved working with large animals and lots of smaller internships at other institutes.

How did you two then decide to work with fish?

Mattias: I more or less stumbled into working with fish. At first, I applied to work with the mice in the institute, but I didn’t get the job. When I started working at the Institute, Dario Valenzano, one of the pioneers in killifish research, had just opened up his lab at our institute and was looking for people to take care of the fish. So, I was offered to work with him and have been working with fish ever since.

Christina: Actually, my work with the killifish started also incidentally. I was originally supposed to work with mice but Mattias needed assistance and so I was assigned to work with him *laughs*.

What does a typical workday look like for you?

Christina: The course of a work day can be very flexible, depending on how many fish lines are currently bred at the institute and how many experiments are running. A typical day starts at 5:45 and end at around 15:00. We usually start our days in the lab, where we prepare buffers and take care of the hatchings before we go down into the animal facility to take care of the fish. That involves feeding and taking care of the aquarium systems we have down there. Feeding times actually vary depending on the daylight-saving times. We then usually take our break around 9:30 before we go back to the lab and the animal facility. During the day we also take care of the overhead work, so we’re ordering supplies and contacting technicians in case anything broke in the facility and we’re maintaining the aquarium systems.

Mattias: Since Dario went away, the number of active fish lines has decreased drastically and therefore the focus is mostly on the lab work and facility management. It’s honestly a bit frustrating for Christina and me, because we would love to do more hands-on work with the fish instead.

What do you like most about your work and the work with killifish in particular?

Mattias: As Christina mentioned, there is a lot of flexibility in how we arrange our day and no absolute strict time tables like in mouse work. Additionally, I like that we get to work both in the animal facility and in the laboratory, including hands-on and computer work. Also, being able to see the fish embryos develop in real time through the translucent egg shells is great and it’s fun to see the fish hatch and grow. While the fish might look alike for a layperson, with some practice you can spot their distinct individual colorations and can easily identify individual fish. You kind of grow attached to them.

Christina: I also like the laboratory focus of our work, as it allows me to learn and apply very specialized techniques. For example, I specialized in sperm freezing to allow for the conservation of fish lines. Just as Mattias, I also love seeing our fish grow up. They’re kind of like children to me and Matthias, since we take care of them starting from birth and long into old age. I look forward to going to the fish every day.

What is the most challenging part about your job?

Mattias: The management and overhead work, actually. It takes a lot of times to order stuff and contact support and we would rather invest that time into animal work directly. Also, documentation of our work is a difficult topic. In Germany, all animal work needs to be documented thoroughly. While there exists good digital documentation software for mice, that software is often not suitable for the very short-lived killifish. So, we still do most of the documentation per hand and are continuing to look for suitable software.

Christina: We would really like to reduce the organizational work load and change our work flow. We want to restructure the facility into a service provider for the scientists, where they can order breedings and genotypings of fish lines and we take care of that.

What would make your job easier? Is there anything that specifically the scientists working with you could do to help you?

Mattias: A secretary *laughs*

Christina: We would appreciate it if people tried to communicate with us more and if they shared the experimental plans and designs with us. A lot of scientists often keep their ideas and plans very close  to themselves when sharing those with us would make it much easier for us to help you. Also, please start cleaning up after yourselves. We can now identify individual scientists by the messes they leave behind *laughs*.

Is there anything in your job that nobody of your colleagues is aware of? Anything you keep secret?

Mattias: Yes, that we are actually working and not just taking breaks *laughs*. But seriously, there is almost no communication between the downstairs animal facility and the rest of the institute, so our whole work must seem kind of mysterious to everyone else. However, everyone is welcome to spend a day with us to see what we do every day.

Christina: This isolation from the rest of the institute actually forged Mattias and me into best friends, simply because we spend so much time together. So maybe that is something that a lot of people don’t know about us.

Did your animal caretaker training help you in everyday situations so far?

Christina: Due to my training as an animal medical assistant, I was able to help my parents when one of their pets got sick, but I couldn’t apply it in any other situation yet. I also usually don’t mention my job in everyday talk. There is still a lot of prejudice against animal caretakers in science, sadly.

Mattias: I can apply my training every time I deal with my cats and dogs. I’m also really open to talk to people about being an animal caretaker. Sure, there is a lot of prejudiced people, but in my experience, it helps talking to them about their misconceptions.

You already mentioned that you have cats and dogs at home, Mattias. Do you both have more animals at home?

Mattias: Yes, a whole zoo! Two dogs, two cats and two parrots. I had them all for at least 5 years now and some of them for more than a decade.

Christina: My parents own half a zoo at home but I personally only have some aquariums with shrimps and neon tetras. I really like the different shrimps I have. The fish are kind of boring, though *laughs*.

What do you do to relax from work?

Christina: I like to unwind by drinking a latte macchiato and simply sitting in my flat or a café. Otherwise, I love to decorate, especially flats. Some of my friends have already requested me to decorate their flats and it was amazing!

Mattias: Looking at all my animals, I relax by also being an animal caretaker at home *laughs*. But I also love to draw and paint and I’m thinking of opening an online shop for my paintings. I’m open for commissions, in case anyone is interested!

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