The gwyniad is a fish found in one place on earth: Llyn Tegid (Bala Lake) in the Dee Valley. A member of the whitefish family, it has been isolated in the lake since the last ice age ended approximately 10,000 years ago and has evolved into a distinct form found nowhere else. You will almost certainly never see one — it lives in cold, deep water. But knowing it is there makes Llyn Tegid a remarkable place. This is Experience #67 of the Snowdonia 100.
The Fish
The gwyniad (Coregonus lavaretus pennantii) is a deep-bodied, silvery fish typically 20–25cm in length. It feeds on zooplankton in the cold, deep water of the lake and is rarely if ever seen from the surface. It cannot be fished — it is protected under UK and Welsh law as a species of principal importance for biodiversity. The population has declined due to the introduction of the ruffe, an invasive fish that competes for food, and conservation efforts have included establishing a population in a Welsh reservoir as insurance against extinction.
| Location | Llyn Tegid (Bala Lake) only |
| Status | Section 42 species — protected under Welsh law |
| Threat | Ruffe (invasive) competition; water quality changes |
| Insurance population | Established at Llyn Arenig Fawr |
Why It Matters
The gwyniad is a lesson in the uniqueness of isolated populations. Ten thousand years of separation from its relatives — enough time for evolution to produce distinct characteristics — has made this fish a measure of what isolation in a mountain lake can achieve. There are similar species in the deep lakes of Scotland, Ireland, and Scandinavia: each lake with its own distinct population, each a product of the same post-glacial isolation. The gwyniad is Bala Lake's version of that story, and it gives the lake a depth of significance beyond its considerable beauty.
Experience #67 of 100 — Wildlife category.
Independently written — Snowdon.com