El Nino Fern (Bolbitis heteroclita): Ultimate Care Guide

El Nino Fern, also known as Asian Water Fern or Bolbitis Broadleaf, is a beginner friendly aquarium plant native to Southeast Asia. Similar to Java Fern and other Bolbitis species, the El Nino Fern grows from a rhizome which can be anchored to rocks or other hardscape. This plant has attractive broad green leaves with a slightly crinkled appearance.

Like Java Fern, the El Nino Fern doesn’t need added CO2 to thrive. Added CO2 can benefit this plant by lowering water alkalinity and reducing algae growth. If you aren’t planning on adding El Nino Fern to a high tech tank it’s important to take extra steps to combat algae growth such as the addition of algae eating species like Amano or Cherry Shrimp. While this plant is simple to raise it does have some specific care needs. We’ve assembled this guide with all you’ll need to know to get years of enjoyment from this beautiful and easy-to-care for aquarium plant!

El Nino Fern Care

El Nino Ferns are trouble free aquarium plants which can grow well in low tech tanks with low to medium lighting. This plant grows from a rhizome which must be anchored to rocks or other hardscape. While it doesn’t need soil to grow there should be nutrients available in the water column. These can come from added liquid fertilizers or the presence of nutrient-rich growing soils which slowly leech macro and micronutrients into the water.

A slow-growing plant, El Nino Ferns must be placed near current sources to keep the leaves algae free and provide the plant with fresh nutrients. Once these plants become used to submerged growth in an aquarium they are robust and don’t need frequent care or trimming.

El Nino Fern
El Nino Fern (Bolbitis heteroclita). Edited. Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0

New El Nino Ferns must be placed carefully so they have the best growing environment. Pay attention to the rhizome. This woody part of the plant may resemble a root, but it’s not. The rhizome can’t be buried in soil or it will rot. It must be attached to rocks or other hardscape with thread, fishing line, or a spot of superglue gel. Superglue gel is a favorite method of aquascape enthusiasts, and will allow the rhizome to stay in place while it grows and attaches itself to hardscape. The rhizome can also be laid along substrate, but it’s important that it not become buried by water currents or large aquarium fish.

Are El Nino Ferns easy to care for in an aquarium?

El Nino Ferns are easy aquarium plants without demanding care needs. This plant grows well under medium or low light, and is a good choice for beginning hobbyists with low tech tanks.

Does El Nino Fern need substrate to grow?

El Nino Ferns don’t need substrate to grow and can draw nutrients from the water column. However, the El Nino Fern can benefit from growing in an aquarium with nutrient rich substrate such because this will slowly leach nutrients into the water. If attempting to grow this plant in aquariums without any substrate it’s necessary to make sure enough liquid micro and macronutrients are present in the water column.

Lighting for El Nino Fern

El Nino Fern only needs low to moderate lighting to grow well. This is a good plant for low tech aquariums with dimmer lighting. Exercise caution if growing under bright light. Algae growth can be encouraged by bright lighting and this plant’s leaves are popular targets. If you’re planning on placing this plant under bright light make sure it has strong water currents nearby. Water flow can help keep leaves algae free as well as bring in fresh nutrients.

Temperature for El Nino Fern

El Nino Fern can tolerate most common freshwater aquarium temperatures between 68° and 80° F.

Water pH for El Nino Fern

El Nino Fern likes slight acidic water with a pH range between 6.0 and 7.5. If your aquarium contains nutrient rich growing soil this can help buffer acidity and keep water pH in a healthy range for this plant.

Growth Rate

El Nino Fern is a slow growing plant. Added CO2 can increase its growth rate but not substantially. Many Bolbitis varieties can take as many as two months to grow a single leaf.

Growth Height

El Nino Fern’s maximum growth height depends on environment and care. Expect a maximum height of 4 to 6 inches in most aquariums.

CO2 Requirement for El Nino Fern

El Nino Fern doesn’t need CO2 injection to grow well, but if available it provides a boost to growth rate. Added CO2 may provides other benefits such as reducing algae growth. Algae can build up on El Nino Fern’s leaves because it is a slow growing plant. Added CO2 can help keep algae in check and may be necessary when high intensity lighting is used. Bright lighting combined with high nutrient water can cause algae to spread rapidly in aquariums without CO2 injection.

El Nino Fern Propagation

El Nino Fern propagates through rhizome cuttings. Take cuttings that contain one or more leaf nodes. These cutting can then be attached to rocks or other hardscape with string or a spot of superglue. Make sure to leave the rhizome uncovered. Burying rhizomes in soil will cause them to rot and kill the plant. A good time for rhizome propagation is during regular trimming. Cut sections of El Nino Fern rhizome can be used to grow entire new plants.

El Nino Fern can grow emersed or submersed. It’s possible to grow this plant with the rhizomes in shallow water where it sends out leaves into the open air. This will lead to faster growth but can be a problem when you decide to move it back to a submerged environment. Leaves which have developed in the open air will often die back when submerged. This process is called melting and can be troubling to new hobbyists. Luckily, it’s a temporary condition, and new leaves will eventually develop.

Problems growing El Nino Ferns

El Nino Ferns can be susceptible to black spots, algae, black edges of leaves, and turning brown. These can be the result of high pH, burying the rhizome, or problems transitioning to submerged growth among other problems. Check your water chemistry to make sure it isn’t too alkaline. If you are using substrates which contain crushed coral or aragonite sand they can dissolve over time, raising pH. This can be one cause of block spots or blackening edges of leaves. It’s best to use nutrient growing soil in your tank, such as ADA Aquasoil. This soil can help buffer water acidity which helps your El Nino Fern even if it doesn’t directly contact soil.

If your El Nino Fern’s leaves are turning brown or black check that the rhizome isn’t buried. Rhizomes might look like roots, but they aren’t. Burying them can lead to rotting which can kill your entire plant. If this is your situation it can be possible to rearrange the rhizome so it sits above the soil. If you catch this soon enough it’s possible to save the plant.

When you buy new El Nino Ferns they may have been grown emersed. Leaves grown emersed will often brown and die back before new leaves form. This is called melting and is common with commercially grown aquarium plants, but can be particularly problematic for slow growing plants like El Nino Ferns.

Many slow growing aquarium plants can be susceptible to algae growth. The El Nino Fern’s broad leaves make it a prime target for algae. Algae growth can be reduced by placing this plant near filter outflows of other current sources in your aquarium. Not only will this help keep leaves algae free, it can help to deliver nutrients to the plant. Another choice is well selected aquarium cleanup species such as the Amano Shrimp. Amano Shrimp are excellent and plant-safe algae eaters which can help keep leaves free from nuisance algae.

Where can I find El Nino Ferns for sale?

El Nino Ferns are common aquarium plants which are easily available from local fish stores and online sources. Expect to pay between $6 USD and $9 USD per plant. Many commercially grown El Nino Ferns have been raised emersed. When these plants are fully submerged in an aquarium their foliage can brown and die back in what is known as melting. This is alarming to watch, but common. Eventually new green leaves will appear.

El Nino Fern vs Java Fern

El Nino Fern has a similar appearance to Java Fern. The latter has narrower and longer leaves with a darker shade of green in many cases. Both plants are Bolbitis and have similar growing habits and needs. Both plants grow from rhizomes and neither needs bright aquarium lighting or CO2 injection. Java Fern is a more common aquarium plant, and may be more trouble free than the El Nino Fern. Either of these plants are good choices for low tech tanks where easy-to-care for species are desired.