A thick and healthy Psychedelic Dragonet.
Feeding a dragonet (Synchiropus spp.) fish is a notoriously difficult task. Dragonet fish, known in the hobby as the Mandarin Goby, Psychedelic Goby, Scooter Blenny or Flaming Scooter Blenny will not consume prepared foods unless trained on them and with lots of luck. In the wild they feed exclusively on larval stage animals and copepods. Unfortunately, many other species of fish will also eat larvae and copepods, so it is difficult to maintain the population density required to keep these fish in even the largest systems. Here are some strategies that may work for you:
Feeding live blood worms - they are actually Midge Fly (Chironomid) larvae rather than worms that can be kept in a refrigerator until it is time for feeding. Most Dragonets will eat them without training, they have a good nutrient profile, and are relatively high in fat and calories. They can be cultured, or purchased on a regular basis from suppliers. If purchasing them, you will want to find a supplier who get can fresh batches to you weekly. Kept in a refrigerator they can last two weeks or more, depending on the species. This is usually more economical than purchasing live copepods regularly, as bloodworms have comparatively more biomass for the specimen and for the money.
Culturing bloodworms requires growing the flies throughout their lifecycle, to the adult Midge Fly stage. To culture them take the bloodworm larvae and leave them in a container of water that matches the natural range where your broodstock was collected. If they are capable of handling a saline environment, you can feed them the waste water from your system. Place them at the bottom of a five gallon bucket with a 2 inch layer of mud and 3 inches of waste water, a small air stone, and a floating bioball. The bucket should be sealed except for a hole for the airline. Drill the hole slightly bigger than needed to allow air to exchange, but tight enough to keep the adult flies from escaping. They will lay eggs the same week they grow into adult Midge Flies. Cultures grown outside should be shaded and screened to prevent damage from sun exposure or introduction of unwanted species.
The whole processes takes 1-2 months. They can be harvested with a mesh aquarium net, ideally the mud used would be a slightly smaller grain than the mesh net, so that it can be rinsed away. This can be tested before the cultures are established by sifting the dry mud through the net that will be used later. Multiple cultures started weeks apart can produce a reliable supply of food for your fish.
Most of your fish will eat bloodworms so to get the most of out of feeding them to your dragonets feed your other fish a different food first, and during the target feeding of your dragonet. Use a turkey baster to suck up some water from your aquarium and the bloodworms from the dish you are storing them in. The next step is to acclimate the water in the baster to match the temperature of your system. When ready to feed, place the baster as closely as you can to your fish, without scaring it away before depressing the plunger. This type of feeding process can help train a dragonet to accept easier to source foods, and ensure the slow moving fish has a chance to eat. Alternatively, if you have enough bloodworms, they can be broadcast fed to the tank. This is the method used by most wholesalers in the trade who supply healthy dragonets.
Feeding Brine Shrimp is another way to keep your dragonets fed. Newly hatched brine shrimp have a good nutrition profile, and adult brine shrimp can be "gut loaded" to improve their otherwise poor nutrient value. Hatching brine shrimp from eggs requires separation of the brine and the eggs to prevent additional detritus from being added to the aquarium. New egg free hatching brine shrimp remove this step, but are sold at a premium. Decapsulated brine shrimp have no egg shells, but will not hatch, and will likely not be eaten by your fish in their stillborn state.
Hatched and unhatched brine shrimp eggs.
Gut loading is a hobby term that means feeding a live food with ingredients that you want your fish to ultimately eat, but they wouldn't consume on their own. The live food (in this case Brine Shrimp) should be fed to your fish as soon as possible after they are gut loaded to ensure the most calories are delivered to your fish before the brine shrimp digest the food and swim off the calories. Adult brine shrimp can be feed Selcon according to instructions, a product that has been an industry staple for decades. They can also be fed spirulina (be careful, a small amount of powder goes a long way), yeast, or with phytoplankton. Selcon enriched foods will likely deliver the greatest amount of calories and vitamins to your fish.
Feeding Copepods - the most natural way to feed a dragonet fish is to culture copepods. Purchasing copepods for this purpose can be expensive, the usual sized portion (8 oz) will only feed your fish for a day or two. and add unnecessary nutrients to your tank over time because the copepods are usually fed and packaged with phytoplankton. Feeding phytoplankton to your tank adds nitrate and phosphate, and too much can cause algae blooms. The ideal way to source them is by culturing them at home.
While culturing them in a refugium will ensure some density in your display tank, a separate culture system is the most reliable way to ensure a high enough density of copepods in your display. Culturing copepods to feed to dragonets starts with picking appropriate broodstock. You will want to feed benthic copepods, and avoid Gammarind Amphipods which are less likely to be eaten by your dragonet, and whose cannibalism and predatory behavior on other copepods makes high population densities in your display hard to maintain. There are many species of pods that would work in various stages of their life cycle, but Tisbe sp. pods are the preferred choice because they are best fed as adults and are readily consumed by the fish.
Copepods can also be gut loaded to improve their already strong nutrient profile. Delivering astaxanthin rich foods to your copepods is believed to subsequently improve your fish's coloration.
To culture copepods fill a 5 gallon bucket halfway with water at salinity levels that are best for reproduction of the species you are culturing. This is usually lower than the salinity level of your display tank. White semi-translucent buckets are best suited for this purpose because they allow you to visually monitor water levels. A sponge filter with an encased weight should be added next, as well as sinking and floating bioballs to increase the filtration capacity of your culture bucket and available surface area. Mark the water level with a black magic marker, so you can know what amount of water you have to add to make up for evaporation over time, or the saltwater water lost after harvesting. Drill a hole in the top of the air bucket a little larger than the airline to feed it through to facilitate motion and air exchange. Feed the copepods small foods regularly rather than large feedings for a more stable culture. To harvest, place bioballs or the sponge filter in a separate container and rinse with saltwater, the copepods will dislodge and fall into the separate container, which can then be added to your tank. A 10 micron sieve is useful for water changes, as it allows you to siphon the bottom for detritus while catching the copepods that are inadvertently vacuumed out. Conservative feeding will help reduce the need for water changes.
These strategies will help you succeed with a dragonet, but you should be aware that all of these feeding strategies require a lot of time and effort on your part. Even if you are willing to spend a large sum to keep your dragonet happy, you still have to place and accept regular orders. You don't want to turn this hobby into a chore, and keeping a mandarin fish can quickly become just that. There are other beautiful fish for your aquarium that won't consume as much time that are better choices for nearly all aquarists.