Complete Guide to the Goldfish Plant

12 Sep 2022

This perennial gets its name from its nectar-filled orange flowers, which appear in the warmer months, looking much like chubby little goldfish, complete with a set of pouting lips.

It is a highly rewarding plant to keep due to the volume of flowers it produces and the speed at which they appear during the summer months.

As cascading houseplants, these beauties can be added to hanging baskets or sat upon a shelf as a trailing and overflowing houseplant.

Plant Characteristics

Goldfish or guppy plants are rapid bloomers with small succulent-like leaves and are endemic to Brazil.

Their Scientific name is Nematanthus gregarious, from the Nematanthus genus, and it belongs to the Gesneriaceae family, just like its distant cousin, the African violet.

Fun fact: In light of its attractive bulbous shape, this subshrub is also commonly called the clog plant.


Here is a peek at the most popular varieties closely related to the Nematanthus gregarious.

  • Columnea gregarious: produces perfect little pouting blossoms with an orange glow.
  • Variegated Columnea: has lovely cream and green variegated leaves and a bulbous orange guppy-like blossom.
  • Columnea Banksii: produces yellow, bright flowers and simple green leaves.

Fun Fact: Black goldfish is another common name used for this houseplant. This name refers to the sight of the bright goldfish-shaped flowers leaping against a backdrop of dark glossy leaves.

How Big Does It Get?

Nematanthus gregarious grow to about 1.6ft (48.7cm) in height and achieve 3.3 feet (100cm) in width. 

How Fast Does It Grow?

Nematanthus gregarious grow roughly 2 inches (5cm) every year. While it’s slow to grow, it’s a rapid and aggressive bloomer, so well worth the wait.

How Long Does It Live?

With the proper tender loving care, your Nematanthus gregarious should give you 10 glorious years. A decade of beautiful orange blossoms and glossy leaves is a treat for any indoor gardener.

Is It Toxic to Cats, Dogs, and Humans?

Choosing non-toxic houseplants is often underestimated; luckily, this one is considered non-toxic to pets and humans, making it perfect for a family home.

Fun Fact: As with dragon plants and English Ivy, Nematanthus gregarious are known as “green purifiers” for their ability to clear the air of toxins.

Goldfish Plant Care

Here are some guidelines for how to care for this easy-going houseplant. Although it’s considered low maintenance, giving them the best care possible is essential so that they give you their best display.

How Often Should It Be Watered?

Water your pot plant roughly once every two weeks, especially during the warmer months. This routine can be pulled back to once a month during the cooler winter.

As this houseplant is native to tropical Brazil, it is happiest in damp but not wet or water-logged soil as it is not as thirsty as most tropical plants; it can tolerate dry periods for much longer.

It would be best to allow the top 3 inches (7.6cm) of soil to dry out before watering it again to limit the chance of over-watering.

When watering your Nematanthus gregarious, try not to splash water on the leaves as this can cause damage. Try to use filtered chlorine-free water that is at room temperature.

Drainage Guidelines

Allow for good drainage and aeration for your guppy houseplant. Layers of stones, gravel, or broken pieces of sponge in the bottom of the pot will do the trick.

When and How to Prune It

This houseplant will flower for longer and more proficiently if you trim and prune it often. Trim it every 2 weeks in the growing season and keep the stems around 13-18 inches (33-45cm) long. This routine will also ensure a lovely bushy-shaped plant.

Once the flowering period is over, snip off the weaker stems and leaves as the houseplant enters a more dormant phase.

How Often and How to Repot It

Only replant your Nematanthus gregarious every two to three years. These houseplants perform much better when they remain in the same pot and are rootbound for a long time.

Limit your new pot size to one size up or around 1-2 inches (2.5cm-5cm) larger.

As with most houseplants, choose a pot with suitable drainage holes.

To replant your Nematanthus gregarious, follow these steps:

  1. Gently remove the houseplant from its current pot.
  2. Add a layer of stones or gravel to the bottom of the pot.
  3. Fill the first third of the pot with well-draining potting soil.
  4. Place your Nematanthus gregarious inside the new pot and top it up the pot with extra soil.
  5. The stems should be at the top level of the soil.

There is no need to press down on the soil as the guppy houseplant prefers an aerated environment.

Optimal Environment

While the goldfish plant is a happy-go-lucky houseplant pet, providing it with the right environment will mean the difference between a few flowers and an abundance of them over the warmer months.

Please take note of the guidelines we provide on the different elements of its environment.

Light Requirements

As with the cast-iron plant, this beauty is partial to bright, indirect light. It lends itself to being placed on a kitchen windowsill where it can receive mostly filtered light.

Nematanthus gregarious will be OK with a few rays of bright, direct light during the day; make sure that it’s not getting a lot of harsh afternoon rays as these may lead to the leaves becoming burnt.

Best Potting Soil

As with most members of the Gesneriaceae family, these houseplants prefer a porous and rich potting medium. Like the nerve plant, they thrive in slightly acidic soils at around a pH of 6.5.

Soil labeled for either orchids or African violets is usually a good choice as Nematanthus gregarious is used to growing on trees in the wild instead of in the soil. Hence it enjoys very well aerated mixes.

Should you wish to make your own mix, a good ratio to follow would be:

  • one part perlite
  • one part fir bark
  • one part peat moss

Due to its aeration, this rich mixture will allow the root system to breathe well. Take note that heavy soil prone to waterlogging can lead to root rot and fungal infections with this houseplant.


To help them along during their flowering season, feed them with a micronutrient-rich liquid fertilizer twice a month. Spray the mix directly onto the soil.

A 30-10-10, suited for acid-loving plants, will be perfect for this houseplant pet.

Pot Size and Type

As Nematanthus gregarious enjoy tight spaces for their root systems, choose a container that is only 1-2 inches (2.5-5cm) bigger than the rootball.

Goldfish plants can be planted into pots, preferably terracotta or clay, so that the roots can breathe. They are also commonly hung and grown in hanging baskets, enabling the plants to cascade and trail beautifully.

Temperature Range

Goldfish houseplants are in their element in a temperature range of between 65 – 75°F (18-24°C).

This is the environment these plants would enjoy in the wild, under a canopy of trees in a tropical rainforest.

Humidity Level

Moderate to high humidity levels will be perfect for this houseplant; work on around 50-60%. Your houseplant will be grateful for a room-temperature misting of the air around them.

Your houseplant will also appreciate a humidifier during the dry months.

Can They Live Outdoors?

These plants will thrive in USDA hardiness zones of 10-11. So long as the plants are situated outside, in an area where the air is not too dry, and the plant can enjoy indirect, bright light, it will be happy.

Make sure to bring the Nematanthus gregarious indoors as soon the weather cools down.

If you decide to have them outside, they will likely want to grow taller than 3 feet (90cm) but pinch off the top leaves and stems to keep them in good bushy shape and flowering state.

Flowering Information

These plants are beautiful bloomers, offering their owners their most impressive display during the springtime.

For a bevy of flowering beauties, group them with a bird of paradise and a canna lily.

When Do They Bloom?

It takes 6-8 weeks until you will see the flowers bloom on a new plant. They flower in spring, summer, fall and winter if their conditions are good. A large goldfish plant can deliver about 100 flowers at a time.

How Long Do the Flowers Last?

If the environment is correct and your houseplant is thriving, each bloom should last about 20 days.

How to Get It to Bloom

Your houseplant is highly likely to bloom, given the right conditions. Here are some of the contributing factors to it flowering.

  • Enough light is important. Bright, filtered and consistent light will fuel the growth of flowers.
  • Correct watering. Your houseplant will appreciate being watered once every two weeks in the warm seasons and once a month during the cooler ones. Be sure not to overwater it as this can result in an unhealthy root system which will negatively impact the flowering potential of the houseplant.
  • During the spring and summer, proper natural ventilation is required for the flowers to keep them healthy. Fresh air near an open window will do the trick.

Fun fact: Nematanthus gregarious has received an award of merit from the Royal Horticultural Society.

How to Grow It

Enjoy our recommended methods for growing this plant.

Division and Cutting

How to Divide It

A common and straightforward way to create multiples of your plant is through the division method:

  1. Tip your pot over and gently remove the plant from its home of soil.
  2. Lightly shake and remove the soil from the root system.
  3. Using your fingers and not a tool, separate the roots into 2 or 3 plants, depending on how large your plant is.

You may keep your division in water and grow it hydroponically or in soil.

How to Create a Cutting

You can create a stem or a branch cutting at any stage of the year, although the warmer, more active months are the best time to do so.

  1. Choose a stem without any flowers on it.
  2. Cut a piece below the leaf node, around 4 inches (10cm) long.
  3. Cut the piece off at an angle using a sharp and sanitized knife or shears.
  4. Remove any leaves close to the stem’s bottom.

Goldfish Plant Propagation

Here are some sound methods for propagating these beauties; give them both a go to see which one works best for you.

Propagation in Water

Like the prayer plant and the string of pearls, Nematanthus gregarious can be propagated and grown in water.

Make sure that the water you are using is room temperature and filtered. Use water free from chlorine and other chemicals to give your cuttings or divisions a fighting chance.

  1. Place the stem cutting into a water container and ensure the water only covers the bottom section of the stem.
  2. Once the roots begin to shoot, only the bottom third of the roots should sit in water.

Sprouted Nematanthus gregarious cuttings can either be kept in water and grown hydroponically or planted into soil. You should see roots after 3-4 weeks.

Propagation in Soil

Plant your cuttings into river sand or vermiculite soil, although any well-aerated ground soil should work well.

  1. Choose a few cuttings to plant and ensure the leaves and a few branches are sticking out.
  2. Water the soil and cover it with a thin plastic covering.
  3. Keep the cuttings in a warm area with filtered light.

These cuttings should take around 3-4 weeks to shoot if kept in a lovely warm setting. Once the roots have sprouted and look stable, they can be transplanted into a beautiful pot. The plant will only bloom during spring or early summer the following year.

Plant them in a container 6 inches (15cm) deep with aerated soil for divisions. Pop your division into the pot and make sure not to push down the soil too hard, as the houseplant will be unhappy in very compacted soil.

How to Revive It

There are many reasons why your houseplant may look a little worse for wear; we have listed a few of the most common issues below and potentially what can be done to remedy these problems.

Leaves Are Wilting

While Goldfish plants enjoy bright, indirect light, exposure to harsh sunlight burns the leaves and causes them to wilt.

If the leaves are starting to wilt, move your houseplant into an area with a more diffused light offering. It is not a good idea to sit these plants on a windowsill where they will receive harsh rays of light for hours at a time as they will perish.

Leaves Are Dropping Off

If you notice your Nematanthus gregarious is experiencing leaf fall, you should consider whether it is experiencing a cold injury. Cold injury can occur if the leaves touch cold glass or are too close to a poorly insulated window.

Suppose, after checking, you find that cold injury is not happening. The other consideration is the over-application of fertilizer, in which case you should skip the following two doses and then halve the dosage in the future.

Leaves Are Yellowing

If your Nematanthus gregarious leaves turn yellow, this could be a sign of either under- or overwatering.

If you are overwatering the houseplant, accompanying issues might include the stem becoming mushy, fungal growth or the appearance of brown patches on the leaves.

A solution to this problem is to remove the Nematanthus gregarious from its pot, cut away the rotten root, and replant it in fresh soil.

Should the issue be underwatering, then follow a good watering schedule once every two weeks during the warm seasons and once a month during the colder ones. Increase watering to once a week if the weather is hot.

Stem Is Shrivelled and Mushy

If the stem begins to shrivel and feels soft and mushy to the touch, it is experiencing root and stem rot.

The cause of root and stem rot is overwatering. If you are dealing with root rot, reduce your watering schedule. Use the guideline of once every two weeks during spring and summer and once a month during winter and fall.

Closing Thoughts

This slow-growing gem is one of those you can get excited about. As some would say, a spring display of bright orange flowers or leaping goldfish against the dark background of its glossy leaves will offer you a fantastic show.

This hardy plant requires the simple care of adequate filtered light, nutrients, and an easy watering routine to keep it in good shape. Enjoy all the fun debates around whether the little flowers look more like goldfish or little clogs.

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