Gemfish – Rexea solandri – Southern Kingfish, Hake, Deepwater Species

Gemfish – Rexea solandri – Synonyms = Jordanidia solandri and Rexea furcifera Waite, 1911 

Other names for Gemfish: Southern Kingfish, Hake (Tikati), and King Barrcouta in Australia 

The name Gemfish is in common use for this species in New Zealand. Interestingly David H. Graham makes no mention of the name Gemfish in A Treasury of New Zealand Fishes published in 1953. He referred to this species as Southern Kingfish or Hake (Tikati).  

Arthur W. Parrott in his 1957 book Sea Anglers Fishes of New Zealand also makes no mention of the name Gemfish referring to this species as Southern kingfish. 

Southern Kingfish is not a true Hake.  Hake Merluccius australis is a separate deep-water fish that is also found in NZ waters.  

European Hake 

There is also a separate European Hake Merluccius merluccius, that is also known as Cornish salmon and herring hake. All three species look vaguely similar. 

Description 

Gemfish belong to Gempylidae, or the snake mackerel family and are closely related to the much-maligned barracouta which is thinner in the body, lighter, and found nearer the surface. Although similar in appearance to barracouta, Gemfish are heavier set in the body, have larger eyes, and unusually have two lateral lines, the bottom of which is wavy from the rear dorsal fin back to the tail.  

The heads, jaws and teeth of the two species look similar. There are three long dagger-like teeth at the front of the top jaw and two widely separated fang-like teeth in the overshot lower jaw of both species. The teeth of the Gemfish are longer and backward sloping. 

When freshly caught the Gemfish is an attractively colored fish. It is bright iridescent blue above, and silver gray on the sides and underneath. After capture their coloration quickly becomes much darker and often quite blotchy. 

There is a deep black spot on the first dorsal fin between the first and third spines. 

There two small finlets between the second dorsal fin and the tail.  

Large specimens can reach 1.8 meters in length.  Known to reach at least 10kg.

Where to Find Gemfish 

This is a deep-water species found between 150 and about 500 metres. According to Lary Paul in New Zealand Fishes – Identification, Natural History & Fisheries, Gemfish are recorded down to 800 m. Their numbers vary greatly from season to season. As a general rule Gemfish are caught in shallow water in summer and deep-water during winter.  

They are a mid-water predator but move up and down in the water column seasonally in search of prey. 

David H. Graham who studied sea fishes at the Portobello Marine Research Station near Dunedin from 1930 to 1933 said Southern Kingfish were common outside Otago Harbour, at or little above the bottom in 10 to 20 fathoms over the summer months, and deeper between 20 (approx. 36 m) and 120 fathoms (220 m) in the winter time. Graham said they we’re occasionally caught in just three fathoms (approx. 5.5 m). 

They were caught both by line and commercial trawlers at North Reef two and a half to three miles off Otago Heads, Cape Saunders and between Hayward point and Otago heads break-water. A good place to target them is over sea-mounts rising up from deep-water.

Gemfish are caught all around New Zealand but are more abundant south of Napier. 

What do Gemfish eat? 

The stomach contents of the Gemfish fish examined by David Graham show them to have been feeding on sprats, red cod, small barracouta, Opal fish, seaperch, as well as squid, octopus and whalefeed (krill). 

How to Catch Gemfish  

Deep sea anglers usually encounter Gemfish when fishing for bluenose and groper in deep water. They’re usually not targeted but instead come aboard as a mostly unwanted bycatch.  

Many less knowledgeable anglers tend to throw them back over the side because they’re so ugly looking. The flesh of the related barrcouta is often invested with nematode parasitic worms. Anyone who has filleted a barracouta will know what I mean. The Gemfish just looks too much like a barracouta for most Kiwi anglers who won’t eat them if they know what they are. Gemfish are unlikely to be infected with nematode parasitic worms. 

Tackle for Gemfish 

Gemfish often hit groper baits in mid-water either on the way down or on the way back up. Your terminal rig needs to be made of very heavy monofilament with heavy traces of at least 80kg breaking strain so as to avoid having your hooks bitten off.  

Use big 14/0 tuna circle hooks which will almost aways take the aggressive Jemfish in the corner of the mouth. The heavy weight of the sinker needed to take your gear down in deep-water will be sufficient to set the hook so there is no need to worry about striking. Back in the day when everyone still fished with 24kg monofilament on their reels you had little chance of feeling a bite anyway with over a hundred metres of line out. The very low stretch of braid is so much better for deep-sea fishing. With the tuna circle hooks striking is still unnecessary.  

It is always worth connecting your sinker with lighter line so that if your rig does snag on the bottom, you have a good chance of busting it off and still getting your fish up to the surface. A good way of doing so is to tie your sinker to the bottom loop with a short length of 30lb mono which is sure to break before your mainline or the terminal rig’s backbone. Here is a basic groper rig employing Power-baiter hooks along with keepers to help keep the bait on. 

Like barracouta their teeth are very sharp and can easily inflict a nasty wound to the unwary angler. For this reason, gaff them in the mouth and whack them on the head with a bat. 

When it comes to bait for Gemfish they are not in the least bit fussy. Squid and barracouta cut baits will do just fine.   

Are Gemfish Good to Eat? 

Yes, they are. The flesh is white, flakes easily, and has a delicate texture. it has a high fat content and produces an excellent smoked product. They are best cooked and eaten fresh as they have a tendency to become soft after being frozen. Gemfish make excellent eating. They can be difficult to fillet because of there are many small bones.