Knysna Seahorse

The Knysna seahorse is a small, delicate creature with a standard length of up to 12 centimetres. Colouration is strongly influenced by the surrounding environment and a particular individual's mood. It varies from pale green to brown (often with darker speckles) to purplish black. The body is encased in a series of bony rings, the snout is relatively short, and the neck arches in a smooth curve without a crown. The tail is muscular and is used to grasp a mate during courtship or to anchor the fish to the substrate.

The Knysna seahorse occurs mostly in areas with high vegetation cover (at least 75%), and is associated with five dominant aquatic plants: Zostera capensis, Caulerpa filiformis, Codium extricatum, Halophila ovalis and Ruppia cirrhosa. While the Keurbooms and Swartvlei estuaries both have very dense plant cover, vegetated sites only make up approximately 11% of the Knysna Lagoon. Large areas of habitat in this system may thus be unsuitable for H. capensis. The fish is well adapted to estuarine habitat and can tolerate a wide range of environmental conditions, such as salinities ranging from 1–59 ‰. Breeding occurs in the austral summer when water temperatures approach 20 °C. Sexual maturity is attained in about one year at 65 mm standard length.