The mud-lover of the flatfish family. This is a fish that has made peace with the muck. Yellowbelly flounder look similar to common flounder. But the underside is a distinctive bright yellow. It serves as a warning to predators. This fish lives in some pretty disgusting water. The upper side is dark and mottled brown. It provides perfect camouflage against the muddy, tannin-stained water of a deep estuary. A fish that wears its habitat on its belly. The colour matches the environment. The disguise is complete. Oxygen-deprivation specialists define this species. Yellowbelly flounder live in water that would suffocate most other fish. Warm, stagnant, low-oxygen mudholes at the top of the estuary are their home. They have evolved a higher tolerance for low oxygen. They can survive in conditions that would kill a snapper or kahawai. This is why they are often the only fish left in a polluted or degraded harbour. A fish that breathes where others cannot. The adaptation is specific. The niche is narrow. The competition is absent. A muddy, earthy flavour turns some people off. But purge them in clean, running water for a day or two. The muddy taste fades. A sweet, delicate fish emerges from the muck. It is a transformation. A second chance. The effort yields reward. The patience is required. The result is edible. The perception changes. The value is realised. To catch a yellowbelly is to catch the survivor. It is the tough, yellow-bellied fish that holds on when everything else has given up. Known to Māori as a muddy-water fish, it was often caught in deep, dark estuaries. Other fish did not go there. Its bright yellow belly made it easy to identify. The marker was visual. The location was specific. The catch was reliable. Today it is the flatfish of the industrial harbour. The one that keeps swimming when the water is brown. And the seagulls are the only other things moving. The harbour is polluted. The water is brown. The yellowbelly flounder does not care. It persists in the degradation. It thrives in the neglect. It occupies the space others vacate. It swims through the muck, yellow belly flashing. It breathes the low oxygen. It eats the worms. The other fish are gone. The yellowbelly remains. It carries on in the silt. Unseen. Unvalued by the casual observer. But prized by those who know. It waits for the net. Or it does not. The choice is random. The outcome is uncertain. The fish persists. It has been here for thousands of years. It will be here after the harbour is dredged and cleaned. Probably. The resilience is notable. The adaptability is high. The future is secure. For now. The yellowbelly flounder endures. A testament to the tolerant spirit. A relic of the wild mud. It carries on.