Fish
Blue Butterfish
Centrolophus niger
A deep-bodied, dark blue-black open-water fish of the Cape's cooler offshore waters, rarely seen by shore divers.
Also known as black ruff, cornish blackfish, rudderfish
- Typical size
- Commonly 40-80 cm
- Habitat
- Open water over the continental slope
- Depth
- Surface to several hundred metres
The blue butterfish, also called the black ruff, is a uniformly dark slate-blue to blackish fish with a soft, deep body, small head and a single long dorsal fin. Juveniles drift near the surface in the open ocean, while adults move deeper over the continental slope off the southern and western Cape.
This is a temperate, oceanic species that shore-based spearos almost never encounter, as it favours cool water well offshore. It feeds on jellyfish, salps, small fish and squid. Anglers occasionally take it on deep drop-offs, and its firm flesh is considered good eating.