1. Choosing Your Flora
One of my planted goldfish tanks – Anubias, Myrio Green, Rotala Rotundifolia (before I moved the white fish to my 29 gallon 🙂 )
You’ve probably seen pictures of beautiful planted aquascapes that look like something out of a dream.
They can take months to mature.
Put a couple of goldfish in there and in a week or so and they’ll mow down just about everything.
Goldfish love soft, tender plants.
So unless you manage to somehow get these plants to multiply faster than the goldfish will eat them…
… You’re buying some expensive goldfish salad!
What do you do?
I recommend choosing plants goldfish WON’T eat.
Admittedly, there’s not tons.
First, it’s a good idea to choose your goals before you choose your plants.
Do you want a bare-bottom, low-light tank with low-maintenance plants?
Anubias and Java fern are going to be good options, as they don’t require a substrate or added ferts.
Need something to remove nitrate?
You’ll want a fast-growing plant like Green Foxtail or Hornwort.
Want a heavily planted tank that looks like a jungle?
A combo of Vallisneria as a background plant plus Amazon swords in the mid-ground can help you achieve your goals.
(You’ll probably want to be sure to pick hardy, low-maintenance beginner plants that don’t have a lot of demands.)
As the aquarist, it’s your aquarium – and your rules.
Pick out what you love and what you think will work best for your setup!
Small goldfish are less likely to destroy plants than big jumbo ones with massive mouths.
Fancy goldfish also seem to be less hard on some plants than slim-bodied ones.
Some plants are nutrient hogs and can end up out-competing others for food.
These are probably best kept by themselves.
What works for one person doesn’t work for everyone.
Start out with a wide variety of plants.
Not all plants may like your tank’s conditions, so if you put all your eggs in one basket and choose a ton of one kind of plant and then that plant doesn’t like your water…
… You might lose everything.
But having a variety will let you experiment with finding which ones really thrive.
Read More: Best Plants for Goldfish
2. Lighting for Plants & Fish
Full-spectrum lighting is important to both fish and plant life.
In goldfish, light is used for vitamin D production and skin pigmentation.
Plants need it for growth and overall health.
Without enough light, both your fish and plants will suffer.
Many aquarium lamps need to be replaced yearly because the UV rays stop emitting.
Not so with LED!
A good quality LED light will give your tank what it needs until the bulbs physically burn out.
Read more here about choosing proper goldfish light.
How much light do I need?
Different plants have different light requirements.
Some plants don’t need much at all, like Anubias and Java fern.
Others get fried in high-intensity light…
… But most plants prefer a moderate to high amount of light.
So how long you leave your light on during the day depends on what plants you have.
Typically, 8-12 hours a day is the norm.
More light results in faster plant growth.
Use a large enough full-spectrum LED light for best results at 8-12 hours per day.
Plants need food, too!
Without fertilizers, plants can show all kinds of problems – from poor growth to weird leaf issues.
In high-tech tanks, fertilization is supplied in the form of:
- Root tabs
- Liquid fertilizer dosing (usually used in combination with other fertilizers)
- Powdered nutrients
These are usually made of chemicals.
Fish poop is cleaned out constantly and no speck of dirt is allowed.
You can have a beautiful, pristine tank with flourishing plants that way.
- It’s expensive
- It requires careful monitoring
- It’s not really natural
Which brings me to my next point…
You know something?
I’ve learned that fertilizing plants can be done naturally – and for far less $$.
Think about plants in the wild.
They have what they need to flourish without anyone dumping in synthetic nutrients.
It comes down to two organic food sources for them:
- Mulm/Fish waste
- Soil (yep, good ol’ dirt!)
Mulm is made of old fish food, rotting plants, fish poop, basically dead stuff.
As it settles around the plant roots, it brings them much appreciated minerals and nutrients (as well as CO2).
The plant takes this and turns it into energy for new growth.
Soil works in a similar way and when it comes down to it, plants love growing in dirt!
For naturally strong plant growth:
Consider using either a freshwater deep sand bed for mulm diffusion…
… Or a tank with soil in the substrate (i.e. Walstad-style)…
… Or putting plants in glass jars/pots/bags full of soil like I did in the first tank I showed you.
Both of these can eliminate the need for expensive fertilizers and CO2 units.
With enough plants, you can reduce or even eliminate your need for electrical filtration!
Plants need fertilizers to grow properly in some form or another.
Plants NEED CO2 to survive.
It’s the #1 limiting factor when it comes to growth (source).
Underwater, plants don’t have as much access to this as they do in the open air.
Some people use expensive CO2 injection kits.
And granted, it does work.
You can have a beautifully flourishing tank…
… But there is a dark side to this technology.
Besides being costly, it can be very dangerous to your fish!
Too much injected CO2 can cause oxygen deprivation – and even death.
And there is a VERY fine line.
But if you don’t have enough CO2 in your tank, your plants will not flourish.
And in the worst cases – they will die.
If you want to use them, by all means go ahead.
Lots of people do and have lovely planted tanks.
(For the rest of us…)
If you understand how underwater ecosystems work, you can harness natural sources of CO2 to give your plants what they need.
Carbon is released through many decaying organic processes in the wild.
Soil is an excellent source of CO2.
So is decaying mulm.
And in a goldfish tank, mulm is very abundant 🙂
Using too much aeration/current in the water drives off CO2, so keeping the filter on the smaller side can help… as can not using an air stone.
(Healthy plants supply lots of oxygen for your fish – while consuming the carbon.)
Even very delicate, CO2 demanding plants have been known to thrive in a low-tech tank that contains soil!
They key is figuring out how to successfully merge soil with goldfish 😉
Adequate CO2 will help ensure good growth
The substrate you choose for your planted goldfish tank is an important choice.
If you want a bare-bottom tank, most plants are out of the question…
… Unless you put them in pots or glass jars.
This can work very well.
Plain ol’ gravel (with or without an undergravel filter) is often a recipe for plant disaster.
Unless you use pots.
Or supplement with root tabs/other chemical fertilizers.
A cheaper and more natural route would be to add soil layer below the gravel.
Now the issue with gravel is it doesn’t support fine roots very well – and average pea-gravel can be a choking hazard for goldfish.
I tried dirting a tank with large gravel…
I was a bit disappointed.
The gravel was too large to prevent the soil from penetrating all along the sides of the tank, where it remains looking disgusting.
Large gravel also gives the tank the illusion of being smaller than it really is. 🙁
On the positive side, no choking issues.
And it holds down the plants well.
I recommend using a “gravel” that’s really more of a large-grain sand.
CaribSea has a course, substantial sand called Peace River which is in between a fine sand and a gravel.
It’s PERFECT for dirted or FDSB tanks!
That’s because it can hold down the dirt and/or allow mulm to effectively penetrate through to plant roots.
Other course sands can work in either a thin or a thick layer.
The nice thing about planted tanks is the roots make having a deeper layer of sand possible by preventing hydrogen sulfide buildup.
You can also use the finer sands for cosmetics and plant in pots…
… Or stick to plants that don’t need to root.
- Java Fern
- Other free-floating plants
Fine sands may require frequent vacuuming.
I’m lazy 😛
So currently I only have one display tank with fine sand that I vacuum often.
Some goldfish keepers use something like Flourite or ADA Aquasoil.
The thing is…
It lowers the pH.
It can be hard to clean.
And I’m leery that the goldies will choke on it.
One of my planted tanks contains about 1.5″ layer of Seachem’s Flourite Black Sand.
(Psst… it’s actually clay.)
The finer sand is good for delicate roots.
And the clay allows TONS of good bacteria to grow – even the kind that remove nitrates!
Related Post: Best Substrate for Goldfish
Choose the appropriate substrate for the plants you intend to keep if not using pots.
6. Thoughts on Carpets
Lush carpets of plants sure do make for a beautiful bottom on the tank.
MOST plants that carpet…
… Will be an appetizer for your goldfish.
But good news:
I have talked to folks who have had success growing carpets of Dwarf Sagittaria with their goldfish.
The key seems to be to grow the tank in for at least a month before adding fish.
That way the roots can get established and resist floating up when disturbed by the goldies.
Another option is to add a ton of little Anubias nana petites glued to rocks and placed side by side until you can’t see the bottom.
That can work on sand or bare-bottom.
And they are removable (for maintenance).
My best tip for growing a carpet is to use soil and course sand.
People worry about vacuuming a carpet.
Trying to keep it all spick-n’-span.
Fish mulm is plant fertilizer.
Embrace the crud – don’t fight it – and you will retain your sanity (and have a beautiful tank).
Instead of fighting nature, harness it’s powers to work for you.
These are natural processes that happen in the wild.
And they can also work in a closed aquarium.
If the mulm is piling up to crazy amounts, a light surface sweep with the siphon may be called for.
But the best part of having a planted tank is the plants can use this waste for growth.
And it’s FREE!
Choose goldfish-friendly carpeting plants and accept you will not remove every speck of mulm.
7. Use Little Organisms
This is a little tip from me (at no charge.)
Remember how I told you earlier to stop fighting nature?
This goes for the “pests” too.
I’m talking about snails!
Snails are AWESOME in the planted tank. I keep snails of all sorts in every single goldfish aquarium I have.
They play an important role in the health of my systems.
- Eating algae (MAJOR benefit) and dead plant leaves
- Breaking down waste in the tank (makes it easier for bacteria to process it) adds to tank stability
- Their babies are nutritious fish food
- Some breeds of snails (think Malaysian Trumpet) burrow in the substrate, diffusing nutrients to the plants.
Far be it from me to scheme on how to eradicate them using all manner of poison, traps, etc.
I like to keep as many snails as possible!
I even take their eggs and raise them in separate tanks or containers so I have a continual supply.
And I keep several kinds which do different things.
- Nerites are perfect for glass-cleaning and other broad, flat surfaces. Great for brown diatoms.
- Ramshorns are great for polishing more delicate leaves and replenishing baby snails
- Melatnos are fast-cruising algae destroyers that also assist in delicate leaves
Watching snails is also relaxing 😉
Related: Best Snails for Goldfish