El Nino Fern Care Guide and Planting

el nino fern spotlight

El Nino Fern

The El Nino (Niño) Fern is a great species for planted aquariums. Although quite rare in the aquarium trade, it thrives in a wide range of conditions and is quickly gaining popularity.

Overall, the plant is low maintenance and super easy to grow in any freshwater aquarium.

El Nino Ferns grow as fully aquatic, semiaquatic, and terrestrial plants. This means that they can grow underwater, half in water, and fully above water or planted in soil.

Background Information:

The scientific name of the El Nino Fern is Bolbitis heteroclita. Only two species of the Bolbitis genus can grow fully submerged (this is one of them!). Sometimes, the species name is listed as asiatica.

Also, the fern is native to tropical southeastern Asia, making it a perfect addition to any freshwater tropical tank.

El Nino Ferns can grow both under and above water. This makes them ideal for both aquariums and terrariums.

The ferns grow up to 12 inches (30 centimeters) tall. Leaves can reach lengths of up to 3 inches (8 centimeters) when fully grown.

(If you’re already hooked and don’t have this aquatic plant yet, consider purchasing one from a trusted and verified brand on Amazon below.)

This variety is sold by Mainam on Amazon

Temperature and pH Levels

Most importantly, El Nino Ferns need heated aquariums to grow underwater. The best temperature is between 74°F to 82°F (23°C to 28°C), however, they will survive in slightly cooler or warmer conditions.

Additionally, the El Nino Fern requires a pH between 6.0 and 7.5. Naturally, live plants will raise or lower pH until it’s close to 7, but always make sure the pH is between 6 and 7.5 before planting ferns in an aquarium.

Aquatic plants do best in soft water without heavy minerals or chemicals.

Always test for water hardness and give aquatic plants the softest water possible by using plant-safe conditioners and resources.

El Nino Fern CO2 Requirements

Ferns, like other aquatic and terrestrial plants, need carbon dioxide (for photosynthesis) to survive. Carbon dioxide (CO2) is denser than water and naturally absorbs into aquariums.

However, most aquariums don’t absorb enough CO2 to create a healthy environment for aquatic plants. El Nino Ferns don’t require a lot of carbon dioxide, but CO2 supplements do promote faster growth.

Also, be careful when adding CO2 to aquariums or ponds containing live animals. Too much carbon dioxide can cause animals to suffocate from a lack of oxygen or may cause dangerous swings in pH levels.

Here Are Some Ways to Increase CO2 Levels in Aquariums:

  • Chemicals – Buying CO2 injection kits or dissolvable tablets at pet stores is a great way to put carbon dioxide into tanks. Simply follow the product’s instructions to add a consistent supply into an aquarium.

– Some downsides are that some injection kits can be expensive or break easily. For these reasons, CO2 tablets are a little more convenient. Drop the tablets into the aquarium when feeding livestock or changing water.

  • Increase Water Surface Area – Increasing the amount of water exposed to air makes it easier for more CO2 to dissolve. Simply remove the top of the aquarium to allow more air to flow over the top of the water.

Another option is to use a shallow container or aquarium. The more water exposed to the air, the better. Because El Nino Ferns grow quite large, some may grow out of the container. This is fine because the plant can pull CO2 directly from the air.

Lastly, it should be noted that increased water surface area won’t always result in extremely high CO2 concentrations. The best option is to always use chemicals or injection kits to provide proper and consistent carbon dioxide levels.

How to Plant El Nino Ferns

el nino fern in bucket

Never plant the fern directly into the aquarium substrate. Soil, sand, and clay-based substrates will cause the roots of the fern to rot if surrounded.

Attach El Nino Ferns to rocks, driftwood, or other decorations. After a few weeks the roots will cling to nearby objects.

Feel free to plant ferns directly in gravel as long as there isn’t any other substrate above or below.

Additionally, if the fern doesn’t stay attached to its rock or driftwood, it can be attached by a fishing line or an aquarium-safe super glue.

Often times jamming the fern between cracks or between rocks will hold it in place until it grows a strong root system.

Also, El Nino Ferns are usually grown emersed (partially in water) or in gel solutions. Because of this, it can be difficult to transition the plant to fully underwater life.

Expect a few leaves to die off in the process (don’t worry, they’ll grow back quick!).

Growing Out of Water

Bolbitis Heteroclita grows out of water and well in terrariums, but they need a lot of moisture. They are prone to drying out quickly.

As a result, ferns should be misted at least one a day. Keeping them in an enclosed environment that holds moisture is ideal.

Try to aim for a relative humidity level of 70% or higher. For reference, most homes are between 30% – 50% relative humidity.

Devices that measure relative humidity are available online and instore for a few dollars. Always keep one in terrariums that have living creatures, especially sensitive ones like frogs and reptiles.

Also, El Nino Ferns are nontoxic and safe for fish, amphibians, and reptiles.

Additional El Nino Fern Care Tips

Aquatic ferns prefer to have strong water currents.
Aquarium power or sponge filters help create surface disruption and water currents. Water movement slows algae growth and pulls more CO2 into the water.

Consider using fertilizers.
Aquatic plants need macronutrients, nitrates, and nutrients in general to survive and thrive. Store-bought capsules and liquid fertilizers can help boost plant health and growth.

Always make sure fertilizers are fish-safe and use in the correct amounts. Failure to do so may result in the death of fish and aquarium plants.

modestfish.com has a really well-written list of different aquatic fertilizers, and how they are properly used.

Do Not Grow El Nino Ferns in Saltwater.
Bolbitis heteroclita is a freshwater semi aquatic plant. Most individual plants will not tolerate marine environments, although some can adapt to brackish water.

Unfortunately, El Nino Ferns are sensitive to sudden changes in the environment and suffer the transition from growing in semi aquatic environments to fully aquatic.

Trying to acclimate the fern to a saltwater environment will most likely lead to rotting.

Dying Leaves and Reproduction

Usually, a large amount of dying leaves is due to a lack of light or nutrient deficiency. However, El Nino Ferns produce more plants off of their leaves.

First, a spot of the leaf will turn brown and dark, feathery roots will grow out of the spot. In a few days or weeks, the roots will continue to grow down towards the substrate and out from the spore.

Then, after another couple of days, a small green stem will grow from the leaf’s brown spore. It will slowly open up into a new plant.

Eventually, the rest of the leaf decays, and the plantlet will detach and become free-floating. It can be harvested from its tank or left alone to attach to an object and start a new plant.

If an el nino fern is losing a lot of leaves, try using a water stabilizer or treatment to create better conditions. Also, frequent water changes every few days will help prevent a build-up of nitrogen, which is harmful to aquatic plants.


Algae Growth:

Algae growth can become a big issue for aquatic plants in general, especially if they are under bright lights.

This is because algae grows faster than most plants do and can quickly cover the leaves of el nino ferns if not taken care of, slowing down plant growth or causing damage.

It’s a good idea to use a strong filter to reduce the amount of algae cells or spores floating around in the water.

Consistent water changes and even gentle brushing with a toothbrush or aquarium scraper can remove algae from the plant’s leaves, leading to healthier and more vibrant ferns.

Visit Sun Spot Nursery to find more spotlights and plant care guides.

(Remember to consider purchasing one from Amazon as they aren’t often found in local stores!)

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