Opisognathus rosenblatti
| Difficulty | Medium |
| Minimum Tank Size | 30 Gallons |
| Diet | Carnivore |
| Water Parameters | 72-78 F, pH 8-8.4, Salinity 1.021-1.023 |
| Aggression | Semi-Aggressive |
| Size | 3" |
The Blue Dot Jawfish, also known as the blue spotted jawfish, is a small, carnivorous fish with a unique tenancy. Members of the jawfish family will dig into the substrate, creating a burrow as for themselves to live in. For the most part this is where the jawfish will be staying.
Jawfish require a 5″ deep sand bed to build their burrows, with deeper being better. Unlike other species of jawfish the Blue Dot Jawfish loves to burrow vertically rather than diagonally. This creates an issue of keeping the deep sand bed clean. Sand that goes uncleaned for months at a time, as is often with deep sand beds, can create toxic air bubbles. Once these are release they can quickly contaminate the tank, leading to entire system failures. This makes sand sifting creatures incredibly helpful, such as the bristle worm and nassarius snails.
To keep their burrows intact the Blue Dot Jawfish will search for larger chunks of rock, crushed coral or anything it can use to prop the burrow up. To make this easy on the jawfish most aquarists will supply the jawfish with a steady supply of materials until they are done building their home. Often times the jawfish will like a larger shell to cover its den. They will place this cover on the den at night time and remove it during the day.
When the jawfish selects its home you will need to picture where it is and how deep the burrow is. When cleaning the tank we often move rocks around, which can easily destroy the jawfish’s home if we are not careful. Likewise the initial construction of their home may cause rock slides.
Finding a Healthy Jawfish
While this is true of most wild caught fish, the Bleu Dot Jawfish is aggressive towards its own kind. Fighting amongst themselves while waiting to be shipped can create a stressful environment, bad water parameters and infections. Because of this you will need to find a good seller who can either guarantee the fish survives or will at least refund should anything go wrong. A healthy Jawfish is quite hardy and should acclimate into the new tank easily. Remember: The jawfish is often the best fish to add to the tank first, as they will need time to build their burrow and feel very vulnerable without one.
Diet & Feeding
Blue Dot Jawfish are easy to feed, as they will accept both frozen and prepared foods without hesitation. Feeding them will consist of them looking around their home, spotting the food and darting out for a quick bite before returning to their home.
The main concern when feeding jawfish is their level of comfort. Stressed out jawfish, or those unable to build a large enough home, are unlikely to leave their burrow. This makes feeding them quite difficult, especially when paired with quick feeding fish. Try to ensure your jawfish eats properly keep a deep enough sand bed for them to build in, little to no predators in the tank and tank conditions consistent.
When trying to feed the Blue Dot Fish pellet foods you may run into some difficulty. To train them to accept foods simply introduce a small amount of the desired food near the end of their usual feeding. This will help them understand the food is indeed food. training them to eat foods similar to pellets, such as hard flakes, will make the process easier.
Picky Eaters: Almost every aquarist will run into this problem at some point. A fish with what seem to be perfect conditions still refuses to eat. Often the best remedy is to feed the fish what they eat naturally in the wild. For the Blue Dot Jawfish this is small crustaceans, such as copepods. The problem here is that copepods are fairly expensive, with most aquarists even going as far as setting up a culture or large sump to breed them.
Instead simply get a de-shelled frozen table shrimp and grate it into the tank. This produces small, meaty chunks of shrimp that closely resemble copepods. This will entice the jawfish to begin feeding. After doing this a few times you may introduce normal foods and the jawfish should happily accept it.
Behavior & Aggression
Blue Dot Jawfish will have one of two behaviors. They will either sit in their den for most of the day, coming out mostly for feeding or they will swim freely, ducking into their den occasionally. This will depend on what the tank mates are, which order the fish were added in and how comfortable the fish are with their environment. Jawfish who are added first, are allowed to build a deep burrow and have no aggressive tank mates will frequently become aggressive eaters and roam the tank. Those paired with more aggressive fish will likely stick to their burrows and may even require target feeding.
A Blue Dot Jawfish in a small tank
The Blue Dot Jawfish is aggressive towards members of the same species. This typically is not an issue, as most aquarists will only want a single jawfish.
When resting in the burrow you can expect the blue dotted jawfish to assume a defensive personality. They will react almost comically to any passing fish and watch everyone one in and outside of the tank.
Fish that swim into burrows, such as a large number of gobies, should not be included in the same tank as the jawfish. The Blue Dot Jawfish will aggressively defend his home from any intruders. While they will not typically hurt the other fish, this will cause both of them stress. The jawfish will also spit sand at fish who come too close to its den.
Breeding & Sexing
The Blue Dot Jawfish, while possible to breed in the home aquarium, presents several issues. First they are difficult to sex.Occasionally, during the mating season of spring to fall, male Blue Dot Jawfish will change color. This however will be difficult to spot unless you already own the fish and are very familiar with their colors.
The Blue Dot Jawfish will only begin mating when:
- The jawfish have ample room with dens big enough for both of them.
- Their are no aggressive fish around to threaten them.
- Both jawfish are well fed.
- The jawfish are both in the middle of their lifespan
With all of these variables taken care of and a mated pair the Blue Dot Jawfish will soon spawn. The male will frequently carry the eggs in his mouth, only placing them in the den so that he may eat. This makes it difficult to remove the eggs. Instead you will need to remove the other fish or remove any fry as quickly as possible using a container and not a net. The fry will be released by the male jawfish after a week and will be around 4mm long (http://www.reefkeeping.com) After two weeks these jawfish will be almost 2cm long and will begin to dig their own dens. After a year the fish will be fully grown.
Jawfish must be in the middle of their lifespan to breed. After a certain age the jawfish will no longer attempt to breed, but will continue living for several more years depending on their care.
