Known simply as the spotted grunter in this part of the world, this species is found throughout the Western Indian Ocean from India to South Africa. It favours shallow coastal reefs and often hunts in estuaries. The
spotted grunter is notable for two reasons – its ability to tolerate freshwater, and its unique hunting method. The grunter ejects a stream of water from its mouth, using the force of the water to clear mud away from the hidden crustaceans, worms and bivalves on which it feeds. It can reach up to 80 centimetres in length, and is easily identified by the small black spots that cover its silvery body from the gill opening to the tail fin. Spotted grunter lay eggs, have three sharp dorsal spines and are popular with recreational fishermen throughout their range.
Also known as the tiger perch, the crescent grunter is a highly adaptable species capable of surviving in saltwater, brackish water and freshwater. It is found predominantly in the Indo-West Pacific, although
records of the crescent grunter exist in the Mediterranean as well. It inhabits many major rivers and coastal lagoons, but is predominantly a marine species. Crescent grunter grow up to 27 centimetres in length and have distinctive black stripes arranged in horizontal crescent shapes across their silver bodies. They feed on small fish, and are also known to be lepidophagous – meaning that they feed on the scales of larger fish. This allows them to benefit from the high levels of calcium and keratin present in fish scales without killing their prey.
The javelin grunter is found throughout the Indo-West Pacific, from East Africa to Australia. It favours murky coastal waters with sandy or muddy seafloors, and has been recorded at depths of up to 75 metres. Like other grunter species, it is known to frequent estuaries,
and has a high tolerance of brackish water. When they are ready to spawn, javelin grunter often gather in large shoals at the river mouth, so that juveniles can seek the protection of the estuary upon hatching. Javelin grunter feed on small fish and crustaceans, and can grow up to 80 centimetres in length. They are predominantly silver in colour, although many specimens have a sheen of gold on their sides. They can be identified by a series of small spots grouped to form dark vertical bands.
Other known species of Grunter found on the Aliwal Shoal
- Striped Grunter – Terapon jarbua
- Saddle Grunter – Pomadasys maculatus