Sexing Jawfish

[EvanDeVita]

Hello all,
I want to find a mate for my dusky jawfish, but I cannot find out how to sex them. Does anyone know how?

 

[ichthyogeek]

Marine Ornamental Fish & Invertebrate Breeders • View topic - Jawfish Breeding/Spawning Overview - Opistognathidae

I'm fairly certain that jawfish aren't sexually dimorphic. @ThRoewer 's got a trio of blue spot jawfish, so he might be able to help you figure out if there are any defining characteristics.

Worst comes to worst, you can always go with buying a group of 5 smaller fish and let them work it out by themselves.

 

[EvanDeVita]

Marine Ornamental Fish & Invertebrate Breeders • View topic - Jawfish Breeding/Spawning Overview - Opistognathidae

I'm fairly certain that jawfish aren't sexually dimorphic. @ThRoewer 's got a trio of blue spot jawfish, so he might be able to help you figure out if there are any defining characteristics.

Worst comes to worst, you can always go with buying a group of 5 smaller fish and let them work it out by themselves.

Thanks so much!

 

[EvanDeVita]

Marine Ornamental Fish & Invertebrate Breeders • View topic - Jawfish Breeding/Spawning Overview - Opistognathidae

I'm fairly certain that jawfish aren't sexually dimorphic. @ThRoewer 's got a trio of blue spot jawfish, so he might be able to help you figure out if there are any defining characteristics.

Worst comes to worst, you can always go with buying a group of 5 smaller fish and let them work it out by themselves.

Quick question; all places I see list dusky jawfish as maxing out around 3 inches, but my LFS has these listed as XL Dusky Jawfish. In case you can tell this is MUCH more than 3 inches, it’s probably pushing 8 inches. Is this actually a Dusky Jawfish? I got mine with the hope it would get absolutely massive

 

[ichthyogeek]

I honestly have no idea. Jawfish, while interesting and cool, aren’t really on my fishkeeping radar.

 

[ThRoewer]

Most jawfish are rather difficult to sex. And they are gonochorous = don't change sex.

Of those species where the male keeps the eggs in his mouth (not all Jawfish are mouthbreeders!), males often are larger and have a slightly longer and wider mouth/head.

With BSJ and their close relatives (who are not mouthbreeders) it is the other way around, males are smaller than females, more slender build, and have a narrower head (which still might be a bit longer).

There are a few other things someone could sex them by but none of those is practical (fish stores generally don't like it if you anesthetize their fish to examine them under a microscope) or easy for the average reefer.

The only Jawfish I know of to be easily sexed by coloration is Opistognathus randalli where the females have a black spot at the front of their dorsal fins that males don't have. Top male, bottom female:

I generally go more by gut feeling than science when trying to make Jawfish pairs.

 

[ThRoewer]

Quick question; all places I see list dusky jawfish as maxing out around 3 inches, but my LFS has these listed as XL Dusky Jawfish. In case you can tell this is MUCH more than 3 inches, it’s probably pushing 8 inches. Is this actually a Dusky Jawfish? I got mine with the hope it would get absolutely massive

Fishbase.se lists Opistognathus-whitehursti's maximum length as 14 cm TL, that would be around 5.5 inches.

 

[Cell]

I find a little candle light and some Barry Manilow works well.

 

[EvanDeVita]

Fishbase.se lists Opistognathus-whitehursti's maximum length as 14 cm TL, that would be around 5.5 inches.

Hm.... that confuses me more cause the jawfish in picture is not 5.5 inches. I originally thought it was a foot long before coming to reality. The yellow tail is also sus, but I don’t think I’ve ever gotten a good look at my jaw fishes tail

 

[EvanDeVita]

Most jawfish are rather difficult to sex. And they are gonochorous = don't change sex.

Of those species where the male keeps the eggs in his mouth (not all Jawfish are mouthbreeders!), males often are larger and have a slightly longer and wider mouth/head.

With BSJ and their close relatives (who are not mouthbreeders) it is the other way around, males are smaller than females, more slender build, and have a narrower head (which still might be a bit longer).

There are a few other things someone could sex them by but none of those is practical (fish stores generally don't like it if you anesthetize their fish to examine them under a microscope) or easy for the average reefer.

The only Jawfish I know of to be easily sexed by coloration is Opistognathus randalli where the females have a black spot at the front of their dorsal fins that males don't have. Top male, bottom female:

I generally go more by gut feeling than science when trying to make Jawfish pairs.

Hm. It’s gonna be tough to pair him. If I throw in a Jawfish, will he kill it instantly if it’s a male and let it go if it’s a female? How do they live together? In the same burrow or in the same tank?

 

[shred5]

Dusky jawfish get more than 3 inches. I have seen them way bigger.
I have no idea how to tell gender I have been wanting a pair for a while.
KP Aquatics sells pairs of yellowhead once in a while. I am guessing they are collected that way.

Yellowhead Jawfish - Mated Pair

Yellowhead Jawfish, Opistognathus aurifrons are beautiful fish from Florida. Yellowhead Jawfish start at $18 and mated pairs at $55.

www.kpaquatics.com

 

[ThRoewer]

Hm. It’s gonna be tough to pair him. If I throw in a Jawfish, will he kill it instantly if it’s a male and let it go if it’s a female? How do they live together? In the same burrow or in the same tank?

Most Jawfish live not together with others in the same burrow but each individual has its own burrow a decent distance away from others. They also don't form pairs but rather live in lose groups or large colonies where males usually try to keep a good distance between each other.
The Caribbean yellow head species (there are likely a few) are the only exception to this I know of so far. Ive seen those sharing burrows and forming pairs.

 

[EvanDeVita]

Most Jawfish live not together with others in the same burrow but each individual has its own burrow a decent distance away from others. They also don't form pairs but rather live in lose groups or large colonies where males usually try to keep a good distance between each other.
The Caribbean yellow head species (there are likely a few) are the only exception to this I know of so far. Ive seen those sharing burrows and forming pairs.

ok. I guess there's only one way to find out !