Reef By Steele
10K Club member
How many pods should I have to safely house a Mandarin Goby?
One of the most beautiful fish in the hobby is the psychedelic (green) Mandarin Goby. Actually they are dragonets, but these fish are slated close to expert only and often cautioned to newer hobbyists due to their unique needs.
Unlike other expert only fish species, the Mandy can be successfully kept by aquarists of all experience levels as long as a few things are done to cater to their needs.
Today, many consider Mandarins to be easier as they can be sourced from aquaculture facilities. While this appears to be a plus since these Mandarins have been acclimated to pellet foods, it is still my opinion that for a Mandarin to be fat and happy, copepods play an important role in the successful husbandry of these gorgeous fish. While raising an aquacultured or wild sourced but converted to pellet, flake or frozen foods is possible and done by many of our fellow hobbyists, it is my opinion that an abundance of copepods will provide that fish with a better life.
I hold this opinion, mostly because of the amount of energy these fish expend constantly flapping their fins to hover above the rock structures as they continuously search for copepods on the reef. This constant motion makes the Mandarin one of the species with super high metabolism, requiring multiple daily feedings. While some people are able to feed their tanks multiple times throughout the day, the majority of us are not available often enough to truly meet their needs.
This is where copepods make their entrance. Mandarins hover over the rocks specifically because they are in the constant hunt for copepods, which constitute the majority of their diet in the wild. 1. But just how many and what species of copepods do you need? 2. How do you maintain an acceptable population over the long haul? 3. Do I need to constantly purchase copepods just to safely have a Mandarin?
These are all great questions. And I am going to address them individually.
1. What is the right amount and species of copepods?
This is not black and white, but I will give my recommendations here. First, the right copepods are just or more important than their quantities. The best copepods for Mandarins are benthic (crawling) copepods. The most widely known are the Tigriopus, Apocyclops and Tisbe pods, we also have our proprietary Harpa pod (a smaller cousin of the Tisbe biminiensis). Of these, Tisbe and Harpas are the best of the lot as they are small, making them suited for the Mandarins small mouth, but even more so as they spend almost all their time crawling, and both species are heavy producers, multiplying faster than most any other copepod. Apocyclops are the next pod in terms of value to the Mandarins, even though they spend a small amount of time pelagic (free swimming) they too crawl on the rocks presenting the right attributes for the Mandarins wants and needs. The final and least valuable in terms of serving the Mandarin's best interest is the Tigriopus. For one they are considerably larger making some of them harder for the Mandy to eat. But the most important reason, is that the Tigriopus comes from the California pacific coastline and thus from much cooler water than we keep our reefs. This is one reason why Tigriopus are not known to colonize readily in our tanks. While being an awesome food source for most fish, they are not what we want if we to avoid adding pods weekly to our aquariums.
For amounts, you want to ensure that there are always copepods available for your Mandy. For a new tank prepping for a mandarin, we would recommend 2 times the pods we recommend for a standard reef system w/o what we call pod hunters. So we would recommend a 1/2 gallon of our blended pods or a 32 Oz of our Blended Extreme or Majestic pods (has the Harpas) for a system up to 80 gallons. This is just a general guideline and can be adjusted for a variety of factors. If you have a refugium for them to reproduce away from predation, add the pods well before adding the Mandy, or regularly dose phytoplankton increasing their reproduction you may be able to start with less copepods. On the other side, if you also have scooter blennies, sand sifting gobies, other dragonets or pod hunting fish, it may be necessary to add more pods or be prepared to augment their populations with future purchases.
2. Maintaining a solid population of copepods is realistic and attainable.
First would be avoiding major changes in water quality, especially an ammonia spike. While pods are generally quite tough, extreme ammonia levels will kill them the same as other inhabitants. For this reason, pods shouldn't be added to a new system until the initial cycle is complete, but can generally be added immediately upon the end of the cycle.
Providing adequate structure for the copepods is another factor in maintaining colonies. A large selection of porous rock provides the ideal habitat within the DT (Display Tank), where either rock structure and or macro algae can provide protection and refuge to pods in a sump or refugium. Yes pods can be cultivated in a sump without the presence of macro algae as long as they have something to dwell in to keep them from being swept through the sump and back into the tank with the water flow. Feeding them is another important factor in your tanks copepod sustainability. Regular dosing of live phytoplankton provides the copepods with their natural food source in the wild and also meets their nutritional needs increasing their health and reproductive capacity. Within their life cycle, having strong healthy pods in the breeding portion is vitally important. This is the main reason we sieve our pods at such a small opening to ensure that each bottle holds copepods from eggs to full grown adults. This is highly important for "seeding" a system as their numbers will exponentially multiply when the majority of the pods are reproducing or coming of age than those who have already passed their prime. I cannot recall the number of times we have a customer state that 1-2 weeks after our pods arrived there was an explosion of copepods literally covering their glass.
3. Do I have to continually buy pods to safely keep a Mandarin.
The short answer is no. With proper maintenance and care it is quite probable that a person can maintain a healthy copepods population. That being said, it is important to verify that there are enough pods available, just as you wouldn't quit feeding the rest of your tank. Methods of determining pod presence are varied, but one that our customers use and have results with, is to leave a small area of glass "dirty" while keeping the rest clean. This allows you to observe this spot easily. Every tank is different, but many report pods hanging out during the day while others only see them under light after dark. Possible reasons could be fish activity (pods ain't dumb and do try to avoid fish), flow (they don't generally congregate in high flow areas), ready abundance of food elsewhere (probably the least to affect but why come to the glass if there is tons of food easier to get).
Other methods would be to draw some sand into a pipette and put in clear glass, add water and light from the side to see if pods are swimming in the water (viewing under a microscope also). Same could be done with algae or cyano (I pulled cyano to identify and found it literally teeming with pods once).
4. Observation of your pod hunters will also key you in on their presence.
If your Mandarin, Dragonet, or Scooter Blenny is picking at the rock all day chances are good that you have pods. But if they start coming to areas they don't usually hang out at, may be a cue to add more pods. I witnessed this with a Green Mandarin in QT. Hung out on the rubble all the time, then suddenly the next day it would be clear at the top of the tank circling aimlessly. Upon adding pods he would return down to the rocks and stay there.
Maintaining a population will also depend on tank size and density of predators. Even one Mandy in a small tank can decimate populations as they eat thousands per day, multiple hunters can decimate larger tanks requiring subsequent replenishment. In a larger tank with lots of structure, you will generally find your Mandy sticking to one main area (territory) allowing pods to reproduce and colonize in a different area of the tank maintaining enough density to provide for it's needs.
I hope this helps you determine if a Mandy is right for you. And guide you to providing adequately to create the perfect home for that little guy.
