Yellowhead jawfish

Yellowhead Jawfish Care Guide: Opistognathus aurifrons

The yellowhead jawfish (Opistognathus aurifrons) is one of the most personable of the jawfish group. Hobbyists get the best of both worlds: a burrowing species that happens to enjoy people-watching. And if you provide the best conditions for your little excavator, you can expect it to “spy hop” throughout the day. All it takes is a little sand. (Well, maybe not a LITTLE. We’ll get into that)

Table of Contents: Yellowhead Jawfish Care

Unlike some burrowing fish species (and crustaceans) out there, yellowhead jawfish don’t grow exceptionally large. This provides a bit of relief for anyone interested in adding one of the colorful guys to their collection. Of course – as you’ll find in the links below – that doesn’t cut you any slack in the other elements of their care. If this is your first fish that creates a den in the sand, you may want to hold off.

Yellowhead jawfish have distinctive yellow faces

Quick Facts

  • Common Names: Yellowhead jawfish, Pearly jawfish, Yellow-headed pearly jawfish, Dusky jawfish
  • Scientific Names: Opistognathus aurifrons
  • Size: 5 inches (12.7cm)
  • Minimum Tank Size: 30 Gallons (114L)
  • Reef Safe? Yes
  • Care or Experience Level: Moderate
  • Preferred Diet: Carnivore
  • Original Part of the World: Western Atlantic

Description of the Yellowhead Jawfish

Yellowhead jawfish have – well, yeah, a yellow head. (No one’s ever credited scientists with imaginations when it comes to naming animals) The vibrant, sunny color is usually visible poking out of a den in the sand. And when the jawfish senses the coast is clear? They swim out and hover vertically above the burrow. That’s when you catch a glimpse of the remainder of their lovely colors.

Shading down from the yellow, you get a pale blue or white. Under certain lights, the scales may even catch a greenish tinge. It’s a soft palette that puts people in mind of a shiny pearl. And that’s why you’ll often find the fish listed under the common name “pearly jawfish.”

Yellowhead jawfish only get around 5 inches (12.7cm) in length in the wild. That’s a moderate size for a burrowing species. And, in captivity, they come in a touch smaller at 4 inches (10.2cm). Rather than creating elaborate tunnels through the sand, they craft a simple burrow to duck into. You can see a pair at work in the YouTube video below:

 

The burrow serves as a retreat when they sense any sign of danger. And they’re speedy fish! When a yellowhead jawfish spots trouble, they drop into the opening tail first in the blink of an eye. If they’re comfortable, they hover in the water over the entrance. This provides them with an unobstructed view. And these jawfish love to watch the world around them. It’s one of the things that attract hobbyists.

Yellowhead Jawfish Lifespan

If you’re careful when snorkeling or diving, you may come across yellowhead jawfish throughout the western Atlantic. It takes patience and a keen eye, though. Shadows, changes in the current from your approach, or new noises will send the fish popping into their burrows. Then all you’ll notice are those bright yellow faces peering up at you from the substrate.

On average, the little jawfish survive around five years. Most hobbyists attempt to purchase juveniles, though – especially if they have their hearts set on breeding. Yellowhead jawfish only spawn in the middle of their lifespan. Which happens to fall around the age of two. After that, they won’t produce eggs. It’s something to take into consideration if you want to witness their mouthbrooding behavior. (Don’t worry, we’ll get into that in a few minutes)

Yellowhead jawfish stay close to their dens

Creating the Ideal Yellowhead World

Yellowhead jawfish spread out throughout the tropical Atlantic. You’ll find them around popular tourist destinations such as the Bahamas, Caribbean, and into the Gulf of Mexico. All you need to do is search out patches of sand around the reef. And if there’s some coral or rock rubble in the area, you’ll probably spot the dens.

As with all burrowing species, that deep sand bed is the first item to check off your list. Yellowheads require around 5-7 inches (12.7-17.8cm) to stay happy. You have some flexibility with your substrate, though. They’ll accept a range of grain sizes, all the way up to crushed coral. In fact, you want to include some coral rubble at the top. Yellowhead jawfish use the pieces to reinforce the burrows.

The more jawfish you plan to keep in your saltwater aquarium, the wider the expanse of sand you’ll need. (Yes, they tolerate one another) Everyone needs room to dig an individual burrow. Allow at least 3-5 inches (7.6-12.7cm) between each den to prevent fighting. And ensure you don’t crowd the sand bed with décor. It means a tank full of sand, but you’ll get to enjoy seeing little jawfish hovering over the substrate.

If you have live rock structures around the tank, ensure they’re sturdy. As the jawfish dig through the sand, they may accidentally dislodge the rockwork. You don’t want a fish to end up trapped by a cave-in. Or (worse) you don’t want to see a piece of rock tumble onto your coral. Setting the rock on the bare bottom of the tank will help prevent unwanted accidents.

Yellowhead Jawfish Tank Size

In home aquariums, yellowhead jawfish only reach around 4 inches (10.2cm) in length. It’s shorter than their wild counterparts. And it’s smaller than some of the other burrowing species you can consider. As such, you only need a minimum of 30 gallons (114L) for your little people-watching fish.

Of course, that’s assuming you plan to keep ONE jawfish. If you have designs on a colony of the burrowers, you need to go larger. Each fish needs room to dig a den and hover. If you don’t have that space, you’ll end up with squabbles over resources.

You’ll also want to invest in a tight-fitting lid. A yellowhead jawfish’s first instinct when startled is to dart tail first into their burrow. But some fish go the opposite direction. That results in a spectacular jump – out of the tank. And with their narrow profile, it’s easy for them to fit out of openings.

Even tall tanks won’t prevent an episode of accidental carpet-surfing. You’re better off investing in that lid and adding mesh where your cords and tubes enter. Especially when you first introduce the jawfish into your display tank from quarantine, keep an eye on things. When they’re in a new environment, they’re prone to making a break for it.

Are Yellowhead Jawfish Reef-Safe?

Yellowhead jawfish make their homes in the sand around reefs. They spend their days hovering over their den entrances. And they don’t have time to swim around and harass corals. So you’re in the clear if you want to add them to your reef tank.

Take care, though. Fish don’t pay attention where they fling sand. That digging behavior can irritate or damage the corals. And while no corals were harmed in this instance, you can see the behavior demonstrated in the YouTube video below (to be fair, the clownfish isn’t helping matters):

 

Jawfish use bits of coral rubble to reinforce their burrows. As they excavate the bits of rockwork, they may cause structures to shift. Ensure your corals are safe from potential rockfalls. It’s never intentional (of course), but you don’t want those accidents to happen.

And keep an eye on any of the crustaceans in your tank. Yellowhead jawfish are carnivores. Anything small enough to nibble on becomes fair game. So your shrimp and hermit crabs? They may find themselves harassed if they venture close to the den entrance.

Yellowhead Jawfish Diet

Yellowhead jawfish feed on anything that happens to stroll (or swim) past the burrow entrance in the wild. They’re carnivores that lay in wait for food to obligingly come within reach. (Not that yellow is exactly a camouflage color) You won’t need to struggle with their menu, but their eating habits can cause issues.

In general, appropriately-sized pieces of protein will keep these burrowing fish happy. Any of the following will work:

You can’t sprinkle your offering over the top of the tank and call it a day, though. Yellowhead jawfish don’t stray far from their burrows. That hover habit is about as far as they’re willing to go from “home.” Even when they’re hungry. So you need to make sure you drop their meals close to the den.

If you want, you CAN train your yellowheads to accept commercial fish foods. Mix the pellets among your meaty morsels. Over time, the jawfish will learn they’re as tasty as the usual bits of crustacean and mollusk. And as long as dinner arrives near the entrance, they tend to do fine. (They’re not as picky as some burrowers)

Yellowhead jawfish will defend the perimeter of their dens

Yellowhead Jawfish Behavior and Tank Mates

Yellowhead jawfish are shy. (But you already guessed that) They alternate between poking their heads out of the burrow in the sand and hovering (vertically) over the entrance. When comfortable, you can come across an entire colony suspended in space. It’s a hypnotic dance as the jawfish move up and down through the water column – little yellow and blue bobbers.

Anything strange or uncertain, though, and those pointy tails dash back into the safety of the den. They don’t swim freely through a tank where danger might catch them away from that bolt hole. If they DO stray, though, they’ll race for the surface. So you should NEVER lift the lid on your tank. (If you do, prepare to catch a fleeing jawfish)

And they’re not known for their bravery. They fall on the docile side of the scale, preferring to hide out in the safety of the sand rather than challenge a tank mate for meals or space.

Of course, there ARE exceptions. Yellowhead jawfish need their room in the sand. They aren’t afraid to defend that perimeter from interlopers. And while most of the other burrowing species can intimidate yellowheads, they have the upper fin on gobies. It doesn’t mean you can’t combine the two groups, but keep an eye on everyone. Your jawfish may bully a goby that gets close.

In general, though, yellowhead jawfish find themselves getting bullied. (They didn’t develop that tail first retreat for nothing!) You don’t want to combine them with any of the following groups:

That nervous disposition also presents a challenge. Any sudden movement causes the yellowhead to dash for safety. So you shouldn’t keep active fish in your tank. It’ll lead to excess stress and your jawfish staying in the burrow. This cancels angelfish, butterflyfish, and tangs. Aggressive “feeding frenzy” species will lead to the same problem.

You’re better off sticking to similar calm, slow-swimming species. Look for fish around the same size. Then you’ll keep your yellowhead jawfish calm and brave enough to hover. These groups make perfect tank mates:

  • Anthias
  • Assessors
  • Blennies
  • Cardinalfish
  • Dragonets
  • Gobies
  • Pipefish
  • Wrasses

Yellowhead jawfish are mouthbrooders

Breeding the Yellowhead Jawfish

Yellowhead jawfish are mouthbrooders. It’s one of the coolest aspects of the species. And who doesn’t want the chance to watch a fish carry around eggs and fry? If you’re up to a little extra work, breeding the species is worth it.

You WILL need young jawfish. Yellowheads only spawn in the middle of their lifespan. While young (or old), they won’t initiate spawning. Two is the magic number. Early? Maybe. But if you’re hoping to see that mouth-brooding trick, that’s when you have to aim for.

Unfortunately, telling males and females apart isn’t easy. They look the same, even during the spawning season. You may need to wait for a courtship display to figure out who’s who. (Or you can wait until the eggs show up. Though that’s a bit late) To attract a female, males leave their den and arch their bodies. You’ll see them spread their fins and open their mouth as wide as possible. Since they carry the eggs, the gaping mouth is meant to demonstrate his mouth-brooding prowess.

The best method for breeding yellowhead jawfish is to separate the pair BEFORE they perform the courtship. Of course, that means you need to know who’s paired off. Some hobbyists wait until the eggs get laid, but that means shifting a male into a tank with no burrow. He can’t dig with a mouth full of incubating babies, though. It’s not a good idea. You want established dens for everyone while the brooding’s taking place.

Yellowhead males incubate the eggs in their mouths for 7-9 days. You’ll then see him release 4mm fry. In the wild, they’d disperse into the plankton. You can separate them into a refugium and start them on enriched rotifers. Another 15 days and they SHOULD triple in size. At that point, they’re good to move to the sand and start a burrow. They’ll reach adult size by the end of the first year.

As soon as a male releases the fry, he can spawn again. So if you miss the first brood, this works as your cue to shift your pair to the breeding tank.

Pros and Cons

All burrowing fish come with pros and cons. (Okay, so ALL fish have those lists) Yellowhead jawfish are hard to resist, though. When you see a colony scoping you out from a reef tank, you have to duplicate the scene. And as long as you understand what you’re getting yourself into, you’re all set.

Pros

  • Yellowhead jawfish are smaller than most burrowing species out there, requiring smaller tank sizes – even for a colony.
  • You need to feed them at their burrow entrance, but yellowheads don’t require specialized diets.
  • Yellowhead jawfish are mouthbrooders, with the male incubating the eggs for approximately a week.

Cons

  • Yellowhead jawfish require a deep sand bed of 5-7 inches (12.7-17.8cm) with mixed grain sizes and coral rubble.
  • While docile and shy (for the most part), yellowheads will bully and chase gobies away from their dens.
  • Yellowhead jawfish will spook and retreat from the active movement of other fish or aggressive feeding, remaining within their burrows.

For More Information

If you’re looking for a reasonably manageable burrowing species – one that WON’T turn your deep sand bed into a warren of tunnels – you can’t go wrong with the yellowhead jawfish. They DO have a few quirks here and there, but they’re not as demanding as other fish. And they love to watch people! (You know, when not spooked by sudden activity) But if you need some additional convincing, we’ve got you covered.

This YouTube video walks you through everything you need to know about yellowhead jawfish:

 

Want to know about some of the best yellowhead jawfish tank mates?

Maybe the “burrow bug” bit you. You can’t combine them with yellowhead jawfish, but these species will satisfy your need to cover the tank with dens and tunnels:

Conclusions

A sunny-yellow face peering up at you in curiosity. Fish suspended in a spy hop. A jawfish carting around eggs and fry in his mouth. Who knew you could have everything in one species? Yellowhead jawfish fit the bill nicely. You WILL need to create that deep sand bed, of course. But isn’t it worth it?

References

  • Lieske, E. and Myers, R. 1996. “Jawfish.” Coral Reef Fishes.
  • Michael, S.W. 1999. “Jawfish.” Marine Fishes: 500+ Essential-to-Know Aquarium Species.
  • Michael, S.W. 2000. “The Whimsical Jawfishes.” Aquarium Fish Monthly. 12(8).
  • Schultz, H. C. 2002. “Let’s Jaw About Jawfish.” Reefkeeping Magazine.

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