Brought up in the Scottish Borders with the river Tweed on the doorstep, Cuillien took up fishing when a teenager and developed and learned skills from a few anglers in the local fishing club. He also gave the fly tying a go, and really enjoyed the creative side of that. He worked for Orvis in Kelso for a couple of years and also Edinburgh Angling Centre, where he learned more about products and got to experiment with the latest tackle. This has all taken him towards his dream job: full-time fishing guide with Alba Game Fishing Limited. He also fished in the Scottish National Fly Fishing League for a few years and is currently in the Premier Division. In 2018, he fished for Team Scotland in France in a European Competition, and this year will represent Scotland in the World Fly Fishing Championship, which will be held in Asturias in Spain, in September 2022.