How to Grow A Monstera In A Fish Tank

I already have an article on the general idea of keeping house plants in fish tank, but I wanted to do one specifically on Monstera for a couple of reasons:

1. They do really well in aquariums
2. They look really cool in aquariums
3. They can be NIGHTMARE to deal with

The nightmare thing isn’t even exclusive to fish tanks – Monstera are aptly named, and if you treat them well, they’ll take out your home.

If you’ve never had a Monstera before, this article should answer all your questions.

How to plant a Monstera in a fish tank

There are a few different ways you can go about getting a Monstera into your fish tank, and I definitely recommend either rooting cuttings or aerial roots rather than putting the whole plant in, but also, I appreciate that sometimes we want things done quickly.

Planting a whole plant

First off, don’t do this if you have fish in your tank. The soil from the roots is impossible to completely remove, and you don’t know what nasties you could be adding.

Soil is not your only issue, either. When your Monstera starts producing water roots, some of the soil roots will shed – into your aquarium. They will then rot and create bacteria which could be harmful.

If you’re going to go for the whole plant method, get the Monstera established in the tank before you add your fish.

The first step of getting a whole plant into a fish tank is to remove as much soil as you can. I generally follow a three-step approach:

1. Remove as much soil as you can with your hands. You need to be gentle, but also, Monstera roots are fairly resilient and grow quickly, so don’t worry if you snap a few
2. Wash the roots off. I like to put the root ball in a large plastic bowl in the sink, and blast tap water on them, once the bowl is full I gently brush the roots with a soft toothbrush
3. Soak the roots at least overnight. The cleaner the roots, the lower the chance of root rot.

When you introduce the newly cleaned roots to the tank, you need to add as much oxygen into the water as you can. This will increase the amount of oxygen that the plants can absorb from the water with their soil roots.

Soil roots CAN absorb oxygen from water but not very efficiently, so maximising the volume of oxygen can help a lot.

Rooting cuttings

This is my preferred method because you can pick a big cutting and get the aesthetic you’re going for without having to go through the hassle of cleaning roots.

The biggest obstacle here is keeping the cutting upright, which I’ll go through later.

After you’ve taken a cutting (make sure you have a node if you’re just going for a single leaf cutting), let it callous over, just to minimise any oxalic acid from the wound going into the tank. It can also reduce the chance of rot a little.

Then put the node in the water and wait for it to root.

Putting Monstera cuttings in fish tanks is one of the quickest ways to root them, because the water is warm and well-oxygenated (compared to a glass of water left on the windowsill) and humidity and light are usually pretty good.

Root aerial roots

If you have a really big, established Monstera with an aerial root long enough to go into your tank, this can be a great way of rooting it without having to risk the cutting failing.

It’s the same concept as air-layering (the process of rooting a node before cutting it off the mother plant), except it’s done in water.

This is especially good for big Monstera that have a tendency to droop or have curled leaves, because adding another water source can increase the turgor pressure in your plant and perk it up a bit.

Over time, the aerial root will turn into a water root and start to branch out into a full root system. You can then take a cutting and put it in the tank.

If you establish either one big root system, or several small ones, you could even chop off your Monstera at the base and put the whole thing in, so you have a whole plant in there without having to worry about developing a whole new root system.

How to keep Monstera upright in an aquarium

My favourite way of keeping my Monstera upright in soil is to direct the aerial roots back into the soil so they can support it – it’s easy, quick, and means I don’t have to worry about a moss pole or my Monstera falling over.

Root it in tank decor

This is my preferred way, because it can look really cool:

My Thai Constellation looks a bit sad because she had root rot (putting her in the aquarium saved her) but you can see the process.

We bought a big piece of bogwood with a hole in it and sat her in. Easy. Over time the aerial roots began to attach to the wood and grew down into the water to root.

The aerial definitely grew faster near water.

Set up a breeding trap/sump

A lot of people grow plants in sumps and overflows, which I know little about (my boyfriend is the aquarist – I just stick plants in there) BUT an alternative would be to buy a little breeding trap that you can hang over the edge of the tank and put your plant in there – it would benefit from the warm water and humidity, but you wouldn’t have to attach the Monstera to anything – you could just pop it straight in the trap.

Wedge it

This isn’t the most elegant solution, but it works – just wedge your plant between the lid and the side of the tank. You’ll need a plant with a thick stem, or to move the lid so the stem isn’t put under too much pressure.

I sometimes root cuttings like this – the tank doesn’t have a lid as such, just a piece of corrugated plastic, but it stops the cuttings sliding into the water.

Suspend it from above

We used to have a wooden frame that hung over the fish tank – you can see the Rhaphidophora Tetrasperma growing down it in the picture below.

You could suspend your Monstera from something similar. It would need to be long enough that you could get an aerial root into the water, but have a stem that’s not so thick that it snaps.

It definitely could work if you have a long leggy Monstera, OR you could remove the top cutting (and root that separately), and root the remaining stem.

For example, if I wanted to grow my Rhaphidophora Tetrasperma in water, I’d cut at the line, and stick the circled aerial root the water.

The issue we have here is that we have NO IDEA which axillary bud will be activated next (especially if it were a Rhaphidophora Tetrasperma we were rooting because those things just pick a node at random). Usually Monstera go for the next available node but there’s no guarantee.

How to fertilise a Monstera in a fish tank

I’ve found that there’s no need to add extra nutrition to Monstera in fish tanks. They can absorb nutrients from the fish waste through their roots (provided you haven’t gone massively overboard on filtration).

The constant access to nutrients, even though they’re in small amounts, seems to suit Monstera really well.

If you do want to add fertiliser to your tank, be sure to add ones that are meant for aquarium, because you don’t want to harm your fish.

Is Monstera toxic to fish?

Monstera do contain calcium oxalate crystals, which are toxic BUT this shouldn’t pause a risk to your fish if:

1. You do any pruning away from the aquarium so sap can’t drip into it
2. Any fallen leaves are removed from the tank (you need to do this toxic or not, because rotten matter will pollute the water
3. Only the roots (and perhaps a section of stem) are submerged in the water – but definitely no leaves

We’ve never had an issue with fish eating the roots – even angel fish, which are known as plant maulers. That being said, some fish will eat any plant matter they can get to (yes, I’m talking about goldfish), and some will use the roots as toys (Oscars mainly, but a lot of big cichlids) and can damage them.

To be honest, roots regrow. I think the risk of damage is minimal compared to the benefit of enrichment for bigger fish and increased hidey holes/cover for your smaller fish.

How long can Monstera live in water?

Monstera can live indefinitely in water, and contrary to popular belief, it doesn’t impede their ability to grow to their full size.

The only thing that can stop a Monstera from reaching its full potential is inadequate care (and not enough light).

Fish will provide it with nutrients, but if you don’t have fish (or something similar to create waste) then you can add hydroponic nutrients.

Can Monstera grow submerged in water?

No. Apparently, Monstera adansonii can, but it’s a whole process that honestly doesn’t seem worth it.

If you submerge your Monstera leaves, they’ll rot quickly and poison your tank and any fish you have in there.

If you want fully submerge plants then you need to get proper aquatic plants. You might also want to look at emergent plants that can live both fully submerged and above the waterline.

Will Monstera filter my fish tank?

No. It might provide a bit of filtration, but the amount will vary depending on the size of the plant, time of year, and about a dozen other factors, so I advise to consider the filtration efforts of your Monstera to be an additional benefit – you shouldn’t rely on it at all.

Final thoughts

There’s a reason Pothos are commonly used as fish tank decor – they’re a lot easier to shift around and root and are generally more pliable than Monstera.

That being said, if you can work out the best way to get your Monstera into your tank, whether that’s by rooting cuttings or hanging it from a hook in your ceiling, it’s a great way to add both drama and softness to an aquarium.

If anyone has any tips for keeping Monstera in aquarium, please leave me a comment – we’d love to hear them.