Mangroves in freshwater tanks

[EntoStentor]

A lot of people, myself included, use mangroves as nitrate sponges in SW aquariums and they work wonderfully. Not only do they look amazing and can be grown into many different shapes, but they absorb way more nitrates than sweet potatoes in my tests (don't know about pothos though, I've never grown it in an aquarium). Not only that, but they're extremely hardy and can absolutely cope with variations in salinity and anoxic root conditions. My question is whether anyone has grown them in a freshwater aquarium. I didn't actually know whether they could grow in full fresh so a couple days ago I collected a red mangrove propagule from the beach. I soaked it in tap water for a day and then placed it in a vase with dirt and fresh water (no ferts) for a day. Lo and behold, it already has a huge root network and is beginning to grow a stem. So if they can grow in freshwater, why not plant them in your FW aquarium? I know I'm going to.

So to recap, here are the benefits of mangroves over other commonly used aquarium plants such as pothos and sweet potatoes:

1. They grow very fast and absorb a lot more toxic chemicals such as ammonia, nitrite, and nitrate than other plants.

2. They're incredibly hardy and short of a few bug invasions, they don't tend to have many problems in the aquarium such as not growing roots in the water (for pothos) and leafroll virus (for sweet potatoes).

3. They provide a naturalistic retreat spot for fish to go between their roots.

4. Planted right, they look very aesthetically pleasing.

5. Perhaps most importantly, they're very durable and not even the most notorious plant-wrecking fish will be able to do anything to a specimen that has matured beyond the point of propagule.

With a mangrove, you can not only finally plant your oscar tank, but you can put in a plant that will be able to handle oscar waste, the oscar itself likes (because of root cover), and looks really nice. All you really have to do let the mangrove grow for a few weeks, and then it's ready to go. They're super hardy as well (10/11 PHZ), all they need is at least half the substrate they grow in to be water.

I don't want to dig up the FW propagule to show you the root networks right now (perhaps I will at some point for now I just want to let it grow) but I will attach a picture. This is 2 days since being found washed up on the shore with 0 stem and 0 roots, look at that stem growth! The roots are over 5 inches long at the moment as well.


My camera focused on the dirt on the vase but whatever, you can see the stem.

 

[FLA]

They definitely do fine in freshwater. It is my understanding that the reason you don't see them in freshwater ecosystems is they don't compete well with other more aggressive littoral plants. Salt severely hampers other plants making it the sweet spot for red mangroves. In an artificial environment they should do great.

 

[Fishnerd360]

Interesting research. Some day I’ll want to make a mangrove biotop, but how long would it take till they developed more complex root systems?

 

[FLA]

I have never pushed them hard, but I think they usually grow them for around a year for costal restoration. From what I have seen they can anchor but they do not have massive roots then. I think it takes a while.

 

[EntoStentor]

Interesting research. Some day I’ll want to make a mangrove biotop, but how long would it take till they developed more complex root systems?

They grow fibrous roots as soon as they are planted. These lengthen and turn to wood with age. It takes about 6 months for the tree to grow to a size suitable for a 20 gallon long since you have to keep their trunk and leaves above water. They need about another 6 to really anchor in a substrate. I wouldn't recommend replanting them too often beyond the point when their roots begin hardening.

 

[djsaltynuts]

salt hinders their growth slightly. their niche is being able to survive in conditions toxic to other plants. in areas that arent toxic they are overgrown and outcompeted. if the root system is damaged it is not able to properly cope with the salt. this is why they have trouble going from fresh to salt, but dont lose leaves and dont need acclimated to fresh. it is simply acclimation to a new substrate and new light in fresh water. they are also way less susceptible to root damage since they wont have a problem regulating salt. their nutrient usage really isnt that high and if you look at the amount of mangroves needed to make a significant difference its extremely inefficient and youd need a sump completely stacked full of them to make a big difference(this is why they do completely fine in inert substrate). philodendron plants use allot more nutrients from my understanding. and can be made much more efficient since they grow so much faster and since you can fit much more leaves/plant which determines the amount of photosynthesis happening at once and therefore effeciency.

 

[mattybecks]

Pothos works really well at removing nitrates, and they also seem to grow under any light conditions. Fast growing plants needs materials for building blocks, those come from the water column. The faster the plant grows, the more nutrients it is using from the water column.

This was just a pothos stem I put under water to see what happened, it started growing leaves, fully submerged. Very quickly.