The Snakehead Murrel: How This Fish Breathes Air and Outlasts Drought

The Snakehead Murrel, Channa striata, can breathe air. Not as an emergency reflex, not as a brief surface gulp, but as a sustained physiological system. When dissolved oxygen in a stagnant pond drops toward zero, which happens every dry season across peninsular India, the Murrel simply rises to the surface, opens its mouth, and keeps going. The organ that makes this possible is called the suprabranchial chamber, a pair of air-breathing cavities sitting above the gills, lined with folded, vascularised tissue that absorbs oxygen directly from the atmosphere. It is not a lung, but it functions like one well enough to keep the fish alive when nothing else survives.

In a healthy, well-oxygenated pond, Channa striata breathes through its gills like any other fish. As water quality drops, through heat, decomposition, overcrowding, or seasonal drying, it begins supplementing gill respiration with air breathing, surfacing at intervals that shorten as conditions worsen. In near-anoxic water, it can sustain itself almost entirely on atmospheric oxygen. The chamber walls are richly supplied with blood vessels; gas exchange happens there the same way it happens in gill lamellae, just with air rather than water as the medium. Juveniles rely more heavily on gills; the suprabranchial system becomes dominant as the fish matures, which is one reason adult Murrels tolerate conditions that kill their own young.

When a pond does not merely stagnate but disappears, Channa striata has two options. It can burrow into the mud and enter a state of reduced metabolic activity, surviving for weeks in damp substrate with its air-breathing organ keeping it just above the threshold of death. Or it can leave. Snakehead Murrels are documented moving overland between water bodies, using their pectoral fins and body undulation to travel short distances across wet grass or mud at night. This is not common behaviour, but it is real and has been observed across South and Southeast Asia. The fish can survive out of water for hours provided the skin stays moist, desiccation of the skin, not oxygen deprivation, is the limiting factor on land.

Channa striata is one of the most widely distributed freshwater fish on the subcontinent. It inhabits rice paddies, irrigation canals, village tanks, seasonal floodplain pools, and slow river backwaters from Kerala and Tamil Nadu up through the Gangetic plains and into Assam and Manipur, where related Channa species are equally prevalent. It is a top predator in shallow-water systems, feeding on smaller fish, frogs, crustaceans, and invertebrates. Because it tolerates foul water and survives transport alive for long periods, it has always been a fish of practical importance: sold live in markets, valued in Ayurvedic practice for its role in post-surgical recovery nutrition, and cultivated in low-input pond aquaculture where water quality cannot be controlled. In Tamil it is called Viraal, in Bengali Shol, in Malayalam Varal, the regional names are as numerous as the water bodies it inhabits.

The air-breathing system is the Murrel's most dramatic feature, but it sits alongside a set of traits that make the species formidable in marginal habitats. It is a facultative air-breather, meaning the system switches in as conditions demand rather than running continuously, which keeps metabolic costs low in good water. It is also a nest-guarding species: both parents defend a floating nest of aquatic vegetation and remain with the fry through early development, an unusual level of parental investment for a freshwater fish. The fry are bright orange-red, a colour that fades as they mature into the mottled brown-grey camouflage of the adult. Growth is rapid when food is available, and the fish can reach 90 centimetres and several kilograms in productive systems, though most wild individuals encountered in seasonal tanks are considerably smaller. The combination of air-breathing, overland mobility, parental care, and predatory efficiency makes Channa striata less a fish adapted to Indian ponds and more a fish that has made itself indispensable to them.