The practice of keeping mangroves in captivity as applied to marine aquariums is nothing new. However, it has become increasingly popular as of late. This more than likely has to do with the keeping of mangroves in captivity being mentioned in several publications and popular books by leading authorities as well as advanced hobbyists.
Julian Sprung was among the first to gain notoriety in this practice, keeping several mangroves successfully in a refugium attached to his personal system. Soon, other leading authors and reef-keepers followed suit which have resulted in a demand from the every day reef-keeper.
Mangroves are not true marine plants and are actually found in brackish-water marshes or other areas where fresh and saltwater meet. They have been used to help stabilize the banks of brackish-water aquaculture facilities, medicine, chemistry study, building, agriculture, and even as a potential food source for human and livestock consumption.
A common misconception (though very much in debate) is that keeping mangroves offer the benefits of heavy nutrient export, helping to eliminate phosphates, nitrates and other nutrients in the system. While the fact that mangroves do remove nutrients, they do not compare to macro-algae in this regard and are very limited. This is practically due to their extremely slow growth rate.
Maintaining mangroves is really more for aesthetic value than filtration though limited filtration possibilities do exist. However, the combination of macro-algae and/or sea grasses along with the edition of several mangroves is an option. Since Mangroves are true plants, promoting extensive root development is important and directly related to their potential as nutrient exporters.
If at all possible, purchase propagules instead of seeds. These have the highest survivability rate. Additionally, Rhizophora mangle (Red Mangroves) are probably your best bet. They are among the hardiest species available, as well as the fastest growing.
It is theorized that mangroves originated from the Indo-Malayan region due to the fact that more mangrove species exist in this area than any other.
Some species of mangrove are able to produce propagules that can survive in seawater, floating for periods of a year or longer which is probably how mangroves eventually made their way to other coasts, including the United States.
Roots should be in good condition with no signs of deterioration. Tips of roots will be pink in color which signifies recent growth and a healthy plant. Stalk should be uniformly colored with no signs of unusual dryness or brittleness.
Some dealers sell mangroves with roots incased in small plastic baskets similar to those used with some freshwater aquarium and pond plants. These are ideal but not necessary. However, roots sold incased in substrate-filled baskets are more likely to have healthy, undamaged roots and definitely worth the extra price they sometimes demand.
Like other new editions to our systems, mangroves should be acclimated slowly and carefully. The drip method would probably be your best choice. (using airline tubing to slowly replace water mangroves have been shipped in) In some cases, mail-order mangroves will arrive dry or near to it. In this case, ensure that the temperature of the mangrove itself is at or as close to the temperature of the system water as possible before adding it.
There are a variety of methods for placing newly acquired mangroves in your system, as well as many things to avoid when doing so.
Ideally, marine mud would be a good choice, which would promote natural root development. There are two brands that I am aware of. They are Aragomax Marine Mud by Carebsea, and Miracle-mud by (????).
I'm sure there are other choices as well. Talk to other aquarists, your local society or your local fish-store for more options.
Of course, mud isn't your only option. Mangroves will also root in many types of porous rock as well. Limestone is a favored choice by some mangrove-keepers. A good method for achieving attachment is through the use of rubber bands or by gently sandwiching the roots between two rocks.
Still another method used by some aquarists to promote elongated root growth similar to that found in nature, is to suspend the roots a few inches from the aquarium bottom using Styrofoam floats. This will allow the roots to slowly grow downward until they reach the system bottom and form "legs".
Many aquarists have also had success utilizing various sand beds. If this is the route you chose, placing the roots in plastic plant baskets filled with heavy substrate would be a good idea.
To the right, the same mangroves pictured above but a couple of months later. You can see how each of them has sprouted several leaves. What you can't see is the extensive root growth that extends all the way down and into the sand. I am considering raising my overhead pendant light (standard fluorescent) due to the growth of the mangroves already nearly touching the lamp.
To the left are again the same mangroves with even more growth. You can easily see the method I used to suspend the mangroves off the refugium bottom to promote proper root development, which is now quite extensive.
Ensuring that mangroves have adequate space to grow limits the aquarist as to where they can be placed. Placing them in the main display usually means some sort of modification to the hood as well as the lighting. This probably isn't an option for most. Even in systems with large cabinet-style hoods, intense lighting is sometimes a problem and often is the cause for mangrove failures.
Another option is to place them in the sump though limits as to the height of one's stand often come into play which limits this option.
Still another option exists and one that I highly recommend. A refugium or auxiliary system that sits slightly higher than the display system can easily be powered by a small pump or power-head and allow easy return to the main system. This type of system can provide a beautiful edition to the main system and can easily be lit by incandescent bulbs. This is what my personal system employs.
The biggest problem with providing lighting for mangroves oftentimes has to do with providing too much light or too intense lighting. A good rule is to ensure that ambient temperature around plant extending from water does not exceed 85 degrees. If you can feel heat from your lamp near your mangroves, it is probably too hot.
Moderate lighting from a single incandescent plant bulb or full-spectrum bulb will more than suffice in most cases. Anything over 10K in spectrum is probably not ideal and a lesser rating may prove most beneficial.
If using metal halide lamps, mangroves should receive indirect lighting to avoid being damaged by intensity.
Placing auxiliary or refugium near a well lit window would provide ideal light, though draft and/or excessive heat needs to be taken into consideration.
MAINTENANCE AND CARE
As mentioned previously, mangroves are not natural marine plants. However, they do have amazing adaptation abilities. Mangroves have the ability to excrete excessive salt through their leaves, making survivability in saltwater possible.
In nature, frequent rain rinses salt from mangrove leaves. In captivity, this action must be simulated by the aquarist. This is easly accomplished through daily misting with fresh water in a spray bottle.
Mangroves do not require strong current and are actually negatively effected by it in some cases. Mild to medium current will more than suffice.
Supplementation of iron or other elements is truly not necessary in marine aquariums and can oftentimes lead to unwanted algal growth. Mangroves can easily obtain the elements they need to thrive through the water column in most cases. If you do decide to dose iron or other elements, close monitoring should be emphasized to avoid over-dosing which would lead to other problems.
The mangrove-craze like many others will more than likely soon pass. However, those who continue to maintain them will benefit from their natural beauty which will more than likely remain uncommon at best. I hope that my short article has shed a little light on the subject, even as basic as it is. Mangroves, like any other subject related to marine aquariums is a very in-depth subject and one that can be explored in-depth. I encourage those interested and those not satisfied by this basic information here to research maintaining mangroves in captivity further. The internet is a wonderful resource and information on virtually every subject is but a keystroke away!