Kyphosus (secator)/ sectatrix
| Ecological Descriptors
|Pe (Co, S, M)
||Veg (Cru, Mol)
Body uniformly gray to silver, more or less rounded/ discoid in outline (shape of a rugby/ American football), but with thin yellow to bronze stripes on the body and a stripe, bordered in white, under eye from the mouth to the gill cover. Upper part of the opercular membrane blackish. The young may display pale spots, nearly as large as the eye, on the head, body and fins.
Inhabit shallow waters, over seagrass beds, sand, reef flats and rocky bottoms and around coral reefs, down to 30 m (K. sectatrix). Young chub are found among floating sargassum weeds. Feed on plants, mainly on benthic algae, as well as small crabs and molluscs. Although they mainly feed on brown algae, but also on spinner dolphins’ faeces and vomit. The offal feeding may be regarded as a simple behavioural shift from plankton feeding to drifting offal picking. It was given the nickname rudderfish because it is often seen following ships for the garbage that is dumped.
During each month of the spawning season, chubs are most abundant starting the day of the full moon; group size increases as fish move through the day toward core spawning sites, typically exceeding a group of more than 150 individuals. It displays distinctive colour patterns during spawning
Kyphosus (incisor)/ vaigiensis
Knudsen and Clements (2013) recently revised the family Kyphosidae
K. secratrix: Dorsal spines (total): 11; Dorsal soft rays (total): 11-12; Anal spines: 3; Anal soft rays: 11.
K. incisor/ vaigiensis: Dorsal spines (total): 10-11; Dorsal soft rays (total): 13-15; Anal spines: 3; Anal soft rays: 12-14.
K. bigibbus: Dorsal spine and rays equal in length
K. cinerascens: Dorsal rays higher than dorsal spines
* See below for the recent changes to names and classification of the Kyphosus genus in the Western Atlantic - 2013)
Identification and Differentiation:
It is now known, from DNA analyses, that there are up to 4 Kyphosus/ chub species in the Western Atlantic ( K. sectatrix (Bermuda), K. sectatrix (Bermuda), K. vaigiensis (Brassy/ Yellow), K. bigibbus (Darkfin/ Brown), and K. cinerascens (Highfin/ Topsail/ Blue) and there has been some extensive renaming, with some previously different species found to be just one (K. incisor and vaigiensis). They can be diffificult to differentiate underwater and even form mixed shoals - some require the counting of gill rakers etc to distinguish..see simplified key below:.
(C) Rainer Kretzberg
K. bigibbus (Darkfin/ Brown)
K. cinerascens (Highfin/ Topsail/ Blue)
K. incisor/ vaigiensis (Brassy/ Yellow)
K. sectatrix (Bermuda)