Mangroves in the Aquarium: A "How To" Care Guide

You've probably noticed mangroves in aquariums on social media, popping up at the local fish store for sale or even on your favorite online aquarium hobby retailer - *ahem. Occasionally seen in the background of your favorite ocean documentaries or fishing show, you may not have given them a second thought. However, when we look closer, we see their benefits to inshore and offshore environments, acting as a barrier and a haven.

In the Wild

There are approximately 80 species of mangroves that inhabit tropical waters around the world, bridging the gap where rivers meet the ocean. They have adapted to waters that range in salinity throughout the day as the tides go in and out. From freshwater to brackish, to marine, mangroves are found thriving in practically all conditions.

They are known as vivipary plants, which means the seed develops before detaching from their parent. The offspring are released in a bud-like form known as a propagule into the water to free-float until they are able to settle in substrate away from the competition. This free-floating stage makes them easy to collect, but for the aquarium trade, mangroves (like the red mangrove) are being aquacultured, reducing the impact on natural habitats.

Mangroves shelter coasts from floods and winds, rid the air of carbon dioxide and greenhouse gases, hold sediment in place, provide nesting grounds for birds while sheltering young fish within their entangled root system.  It is these root systems that clean the waters of nitrates, phosphates, and dissolved organics – sound familiar? The fact that these plants provide filtration is reason enough many hobbyists have added them to their systems.

In the Aquarium

Red mangroves (being aquacultured) for the aquarium are perfectly sustainable and are provided by companies like Algae Barn (who also sell copepods and macroalgae for your refugium needs).  Being captively cultivated, they do much better in an aquarium system or even ponds in southern states than those wild-harvested mangroves. The added benefit of being captively grown is that they are less likely to have pesty hitchhikers.

The propagule's long-form will add aesthetics to any aquarium. They look great in open-top, shallow reef tanks, or separate refugiums with macroalgae. So if you plan on keeping one or two, plan ahead and make room: for the roots to grow and branches to extend.

Tips and Care Guide:

• Red mangroves when purchased come in the propagule form at around 6-8” in length, however, can grow up to 30’ tall with expanding root system; ample space will be required. A large sump or refugium may suffice.
• They will do well in waters in the care range of keeping a reef, from 78-83°F, pH 7.0-8.4, dKH 8-12, and salinity up to 1.024 sg.
• Living in the natural sun, mangroves require moderate to high-output lighting if kept indoors, preferably in a warm white spectrum. Ambient lighting coming from a close-by window can also be beneficial or a spotlight separate from tank lighting can be used.
• A deep sand bed is recommended for the mangrove to take root, but the roots can work their way into the rockscape. Nutrients are typically provided by the aquarium substrate, and growth can be further enhanced by providing magnesium, iron, and trace element replenishments.
• Although mangroves do take in phosphate and nitrates, proper mechanical and skimmer filtration is still needed.
• Mangroves export unused nutrients and salt through their leaves. Leaves that fall into the aquarium water system should be collected so they are not allowed to decay.
• Salt is excreted by leaves or by the trunk which can be sprayed with RO/DI water. This salt is extracted from the water, so aquarium salinity levels should be routinely checked to maintain stability in addition to having an ATO system.