Fish Facts

FISH FACTS: Wire netting cods

Wire netting cods, such as this longfin variety, are voracious and ambitious sit and wait ambush predators. This particular fish has lost some of its wire netting appearance due to an unusual pigmentation abnormality on its head that may be due to sunburn.

OF the hundreds of species of fish that sportfishers might encounter on a lurefishing trip to northern Australia, cods are one of your more likely catches. If you flick a lure or jig around likely snags in a mangrove-lined river, there is a good chance you’ll be ambushed by one of the estuary cods, either the brown spot estuary cod (Epinephelus coioides) or the black spot variety of same (Epinephelus malabaricus).  If you’re lucky, you might even fluke a colourful juvenile Queensland groper (Epinephelus lanceolatus). But as you move to coastal headlands or further offshore, your chances of encountering one of the dozens of species of reef cods increase even further. But few will have as much character as the wire netting cods.

There are several species of wire netting cods in northern Australia, all being distinguished by their distinctive mottled camouflage appearance, which consists of linked, pale to white coloured intersecting lines or circles on a brown background. The colour pattern is reminiscent of hexagons, honeycomb or the wire fence netting you would use for a chicken coop, leading to their common names of wire netting, hexagon or honeycomb cods. 

If you’re fishing rocky headlands or inshore coral reef flats and edges, you’re most likely to encounter the longfinned wire netting cod Epinephelus quoyanus. These are the most common species encountered on coastal headlands in north Queensland and along the inshore areas of the Great Barrier Reef, being distinguished by their relatively long (up to 1.5 times the length of the head) pectoral fins, uniform dark brown background colouration with intersecting white lines forming thumbsized hexagonal shapes along the head, flanks and fins. This species is one of the largest of the wire netting cods, growing to around 37 cm long.  Another wire netting cod species that is common in inshore coral lagoons is the honeycomb grouper (E. merra). These look like a longfinned wire netting cod without the long fins, but other differences include some of the white hexagonal lines merging together on the flanks to form longitudinal blotches, and they only grow to around 27 cm.  

Further offshore around the outer reefs, you may encounter the hexagon rock cod (E. hexagonatus).  These grow to around 30 cm and tend to be lighter brown in background colour, with irregular blotches of dark brown, white hexagonal markings and a large yellowish-brown spot just to the rear of each eye.  A very similar looking species that also occurs in the same areas is the 4 saddle grouper (E. spilotoceps).  It is commonly mistaken for the hexagon rock cod, but differs in that it grows a little bigger (to 35 cm), has many more smaller spots on the head and lacks the large yellowish-brown spot behind the eye.  Yet another near identical outer reef species is the one blotch grouper (E. melanostigma), which also grows to 35 cm but differs from the others mainly by having a single large black blotch under the middle of the dorsal fin.

There are several other slightly larger species of cods which may also be encountered in coral reef areas that appear superficially similar to the wire netting types above, but these do not have true wire netting patterns. Instead, they tend to have colour patterns consisting of dark round blotches over a lighter background, which generates an optical illusion of a netting pattern. Such species include the coral rock cod (E. corrallicola) which grows to 49 cm, the snubnose rock cod (E. macrospilos) which can grow to around 50 cm, and the highfin grouper (E. maculatus) which also reaches around 50 cm.  Going bigger again, there are the larger versions of the estuary cods and gropers that migrate offshore as they mature, and the numerous coral trouts and reef dwelling leviathans. One thing is for sure, there’s certainly heaps of variety when it comes to tropical cods in our northern waters.

Back to the wire netting cods, all are “sit and wait” ambush predators that hide under rock or coral outcrops until a likely meal chances close by.  They then dart out with lightening speed to attack their prey which is usually small fish, crabs and shrimps.  They are aggressive for their size and with their large mouths and suction feeding abilities, it is sometimes surprising what they will take on.  These little cod will attack almost any sized or type of lure (or bait for that matter) and studies have shown they are remarkably robust fish that survive catch and release very well, especially as most are caught from shallow water.  Some wire netting cods are nothing if not downright ambitious when it comes to feeding and will take anything they can get their mouths around.  I still remember one 35 cm longfinned wirenetting cod captured on a reef flat on the Great Barrier Reef, which regurgitated not one, but two small turtle hatchlings. One can only imagine what was going through its mind when it thought it also had room in its belly to fit that 7 cm Nilsmaster lure as it swam by…


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