Wearing a flat cap, a blue rubber apron and a pencil stuck behind his ear - the insignia of the fishmonger - John Jones operates at his counter like a fish in water. He holds a filleting knife in his right hand and an 8kg haddock in his left. He makes a precise cut behind the ventral fin and masterfully fillets the fish. Once his work is done, he enjoys a well-earned beer after work. "When I was sixteen, I started selling fish in my uncle's best friend's fish shop - in Clapham South tube station in London. The after-work beer on Saturdays with the "big boys" was the best feeling. Even today, at thirty-four, it's hardly any different," says John on the way to Heidenpeters Bar at the other end of the hall. Although John himself prefers to drink wine with fish, he knows the best flavour combinations between brews and the fish counter: Fish and chips? "IPA or pale ale." Oysters? "Stout. That's what they drink in Ireland. The salty flavour of the oysters and then the strong, creamy flavour of the stout. It's a great match."

In Markthalle Neun, the fish counter resembles a magnificent Dutch Renaissance painting, set up by John every morning with the greatest attention to detail. Colourful mackerels, trout, Norway lobster and oysters are artfully arranged. A fat carp lies next to a round turbot, as if they were part of a late medieval still life. John presents the variety of fresh and salt water on a thick layer of ice. "I always want to show how chaotic and diverse the sea is," he says.

In everyday life, John tends to be a quiet fellow - British reticence perhaps - but when you talk to him about his profession, it just gushes out of him: "Fishmonger, it's not just a job for me, it's a passion." His love for fish already began when he was as a child. "I was always fascinated by fish. When I went shopping with my mum, I was immediately drawn to the fishmonger. The colours, the scales, the variety and the way these strong men handled the fish so delicately - that really inspired me."

Born and raised in South West London, John began his career at Moxon's Fish Monger. "Right from the start, even when I was still cleaning cold stores and counters, it was just a great team and a great atmosphere. And I could brag to my friends that I worked with the strong fishermen." Especially once he was able to put his cleaning rag to the side, get into contact with customers and sell fish, he was hooked. "When customers come back and say: 'That thing you recommended to me was fantastic! The way you told me how to do it. I'll have that again, please!' That feeling hasn't changed, it's still just as good as it was 18 years ago."

After completing his degree in German studies – during which he worked at the fish market in Leeds, John later moved to Berlin, where he worked at KaDeWe, Rogacki and Frischeparadies. Before finding his place at Markthalle Neun, he successfully ran his own fishmonger's shop in Pankow for several years. His regular customers followed him from one fish counter to the next.

In contrast to Germany, a large part of the food culture in the UK is based on fish. "We are an island. The way we deal with fish is different. You rarely buy fish in a supermarket, there's just a trusted fishmonger for almost everyone. Fish is of course a rather expensive product, but we do it here at Frisch Gefischt in a similar way to what I learnt from my boss in the UK: Fish for every wallet. It's not just the premium fish, but also herring, sardines and mackerel that are always on the menu. They taste fantastic and are cheaper than sole."

The acceptance of mackerel, for example has taken a while, says John, because most Germans only know it smoked. "Historically, it was difficult to transport fresh, but that's different today. It tastes great freshly processed. I grew up with it, grilled North Sea mackerel. They are super fresh at the moment and so easy to make. A little oil on it, in the oven and less than ten minutes and it's ready."

So looking at this impressive Fishmonger-CV, what is particular about working with Frisch Gefischt? "Sustainability is a difficult word, but everything in the counter is caught responsibly and sourced carefully. You won't find anything caught with trawls here. If there is a limited supply due to storms, then that's the way it is. Everything arrives fresh and whole." No deep-sea fish or scallops, whose fishing methods destroy deep-sea forests, are sold at the counter. "Hand-dived scallops from Norway naturally cost a lot, but I explain that at the counter. Scallops are something special for me. They're not something you fill up with."

Nevertheless – looking at the big picture – it is fair to say that many stocks have recovered well. "The way I see and read it, a lot has happened thanks to the strict controls, research and documentation. In the 1980s, when things were industrialised, we saw how quickly everything was destroyed and everything had almost been fished to extinction. In the early 2000s, cod collapsed. It has since recovered. If things continue like this, we can continue to eat fish. But in a responsible and respectful way. We should also see fish as animals that have lived and swum and not just as bones and scales. It needs respect. Rather eat less, but eat better."

John concludes by emphasising once again that people should not be afraid of fish. "Many people know about meat preparation, but at the fish counter there is often a bit of fear. Fish is actually easy to prepare. It's better to take it out a little earlier. If it's not quite done yet, just put it back in briefly." In order to provide customers with the best quality and at the same time take away the uncertainty, Frisch Gefischt only offers whole fish - customers can then choose one and the team fillets it. "Many Germans are shy and don't dare to ask."

"So long and thanks for all the fish", you could say, but it's more of an appeal that John makes: Have the courage, try out the variety at the fish counter and discover the simple but delicious preparation options. Because as John Jones shows, fish is not just a food - it is an experience full of colours, shapes and flavours that is worth discovering.