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White-Barred Boxfish

Spiny Boxfish

Shaw's Cowfish

ORNATE COWFISH

Aracana ornata (Gray 1838)

Length 15.2 cms

Comments by Graham Short - "To differentiate Ornates vs Shaw's in the field the head spines (on adults at least of both sexes) tend to point backwards on Shaw's but forwards (or as a minimum directly upwards) on Ornates.

I have found this feature very useful in field, especially for females where the 'base' colours are quite similar in these species.   Even with males, in my earlier diving days I seemed to get so distracted by the stunningly beautiful tail colours/markings that I couldn't always remember what exact species I'd seen i.e. Shaw's vs Ornate on a dive until I got my slides developed. 

This seems amazing to me now as the males are so obviously distinct but my experience suggests others will be encountering similar problems until they've seen lots of these fish of both sexes"

Ornate Cowfish male  Ornate Cowfish male

Colour pattern is different in the two sexes.  Male has blue spotting with the yellow network of narrow lines separating the spots.   The female has stripes.  Paired yellow and blue lines on snout, belly and cordal peduncle.  Tail with five blue loops.  Body is very robust, about pentagonal in cross section; deep keel in adults.  Juveniles smooth, rounded; developed ridges and spines with growth which becomes very large in some females, but usually reduce in males with age.  Usually a double series of large spines over back, starting above eyes.  Some spines along lateral ridges.  Head profile has pointed snout which steepens in males, which develop large hump in front of eyes.  Moderate sized triangular plates form very large hexagonal patterns, becoming indistinct in large adults and covered with small tubercles. Dorsal and anal fins short based. 

The female bears numerous horizontal yellow and blue lines on the body.  the lines becoming wavy and irregular in the upper parts of the side and the back.  The tail is plain.  Ornate Cowfish -Male and Female, Port Hughes Jetty, photo David Muirhead

Distribution - Western Australia, South Australia, Tasmania, Victoria

Remarks - this is our commonest species and is often found on beaches after storms.