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How to Plant a Riparium: A Plan in Seven Steps.

1-V-09 <em>Cryptocoryne</em> Riparium II

1-V-09 Cryptocoryne Riparium II

This article introduces the basic steps inolved in setting up a riparium, a planted aquarium which uses hanging and floating planters to position plants in a partially-filled tank, and is intended to emulate a riparian (shoreline) habitat. The roots of the semi-aquatic riparium plants develop in the water, while their leaves and stems grow in the open air space. Ample underwater space provides habitat for fish and other aquarium livestock. Ripariums combine many options for aquarium gardening design and species selection with relatively low maintenance and other features.

The content of this article is organized with the the following subheadings

  1. Aquarium Enclosure
  2. Substrates
  3. LIfe Support
  4. Selecting & Acquiring Plants
  5. Planting
  6. Fish Selection & Stocking
  7. Enjoy!

1. Aquarium Enclosure

You might already have a tank that will work well for a riparium system. Medium-sized (>20 gallons) to large aquariums work best. While many aquarium gardeners create beautiful planted displays in two to ten gallon enclosures, it is difficult to assemble a riparium in such a small space. Since the tank will need to accomodate the vertical growth of plants it is also beneficial for it to have a height of at least 16 inches.

The following list of tanks available from major manufacturers includes good shapes for riparium compositions:

  • 20 gallon high—24″ wide X 12″ deep X 16″ high
  • 30 gallon—36″ wide X 1″2 deep X 16″ high
  • 50 gallon—36″ wide X 18″ deep X 18″ high
  • 56 column—30″ wide X 18″ deep X 24″ tall
  • 65 gallon—36″ wide X 18″ deep X 24″ high
  • 75 gallon—48″ wide X 18 deep X 20 tall
  • 120 gallon—48″ wide X 24 deep X 24tall

The dimension for “deep” is measured from the front of the tank to the back.

While it may be tempting to select a tall tank with a small footprint, such as a 30 extra-high (24″ wide X 12″ deep X 24″ tall), aquariums of these shapes are less desirable. If the front-to-back distance is short relative to height it is difficult to create visual depth, an important effect in garden deisgn. The tank shown below is a 20 gallon high (24″ wide X 12″ deep X 16″ high) glass aquarium with a plastic frame.

20 Gallon Riparium 27-V-09

20 Gallon Riparium 27-V-09

Riparium displays usually look best with dark backgrounds. Black, charcoal or dark blue backgrounds obscure the dark-colored riparium planters, match the colors of aquarium appliances, and showcase the coloration of aquarium plants. The application of two or three of coats of paint on the outside surface is an easy way to create a durable background for the rear pain of glass. Latex paint functions very well for this and can be easily removed later on with a razor blade. Be sure to thoroughly clean the outside glass surfaces with a mild glass cleaner before painting so that the paint will adhere.

Aquarium Background Paint

Aquarium Background Paint

A well-established principal of art and visual design, the golden ratio, is a helpful concept to use while planning any garden composition. Denoted with the greek letter Φ (phi), the golden section correlates to the number 1.61803…. and is found by dividing a line in two such that the whole length is to the longer section as that part is to the shorter section.

20 Gallon Riparium 27-V-09

20 Gallon Riparium 27-V-09

When working within a frame (such as a fish tank) dividing spaces or placing objects along the golden section is often pleasing to the eye. The unique properties of phi have long fascinated mathematicians, musicians, artists and scientists. A riparium having the air space roughly equal to the golden section of the total height, with the water portion filling the remainder, reliably presents a nice appearance. An easy way to find the golden section of any given dimension is to simply multiply by .62, the golden ratio conjugate. Our model tank measures __” between the inside edges of the top and bottom plastic rims, so the intended water line is marked at __” from the top, 5.7″ from the bottom.


Now is a good time to introduce the hardscape elements around which the plants will be grown. Rounded river stones (below) can help to create a natural river-bottom appearance and are usually easy to arrange in a pleasing way. When this kinds of smooth oval or egg-shaped rock grows algae on one side in the aquarium you can simply rollit over to expose the clean undersurface.

Rounded River Stones

Rounded River Stones

The next shot shows the design opted for in this case–the stones were arranged with the larger pieces toward the back of the tank, and an open corridor passed between two loose groupings.

20 Gallon Riparium 27-V-09

20 Gallon Riparium 27-V-09

The following photograph shows the next substrate layer to follow the stones. Pool filter sand is a widely available and economical option for an aquarium floor. It is inert–it doesn’t retain nutrients for plant roots–so an aquarium with this kind of sand will require fertilization dosing to keep the underwater plants well nourished. Pool filter sand is of a larger and more consistent grain size than many other commercially available sands, such as construction sand, so it avoids compaction and related problems.

20 Gallon Riparium 27-V-09

20 Gallon Riparium 27-V-09

White sand does not stay clean and bright for very long in a planted aquarium. Every small piece of detritus shows up conspicuously on this material, which also often becomes stained with fine algae growth. The next picture shows one additional substrate layer, small rounded pebbles. These will visually break up and obscure small amounts of mulm on the tank floor. It is important to use light-colored substrates for the bottom of a riparium. The emergent plants growing in the above-water portion of the display through shade on the lower part, but sands, gravels and stones like those selected for this tank reflect light, thus brightening the underwater area.

20 Gallon Riparium 27-V-09

20 Gallon Riparium 27-V-09

Life Support

This riparium display will incorporate a basic life support system, comprised of appliances for lighting, water circulation and water temperature control.

A fluorescent strip light fixture, equipped with a pair of HO T5 lamps, will light up the display. The lamps have a “midday” color temperature of 6700°K, which is perfect for healthy plant growth natural color rendering.

(light fixture)

Since this tank will have a light fish bio-load and only about 7 gallons (__liters) of water, it will have only modest water filtration and water circulation demands. The submersible water filter shown below is just small enough to fit below the water surface. This device will move about ___ gallons (___liters) of water per hour.

Aquarium Filter

Aquarium Filter

Submersible filters are economical and easy to set up. However, they have limited circulation power and can clog rather fast. For larger displays a better-functioning option is the installation of a canister filter with intake and return lines plumbed into the tank. The hose fittings included with most canister filters only reach down into the aquarium a few inches below the top rim. An extension modification, shown below, can extend the intake and return down to the water’s surface in the partially-filled aquarium used for a riparium display.

(filter mod)

This small tank will only require a small heater to maintain its temperature. The 50 watt appliance shown below is small in size and will fit below the water’s surface near the submersible filter. This riparium will be maintained at about 76°F (___°C).


Since water filters, powerheads and heaters are scaled to the smaller amount of water in riparium displays, equipment costs and maintenance work might be relatively less than for aquariums filled to the top with water. As mentioned before, although they present engaging displays with rich foliage textures, ripariums also do not require carbon dioxide injection to maintain plant health, a further advantage in this regard.

Selecting and Acquiring Plants

The unifying trait of most of the plants grown in ripariums is their ability to grow their stems and leaves in the air, while their roots develop in water or in constantly saturated soil. In nature, most of these plants grow in wetlands or along the edges of ponds, streams, lakes or rivers. The following groupings organized by their most common applications in horticulture describe most of the plant species and varieties :

  • pond plants, i.e., Mexican petunia (Ruellia brittoninana); rain lilies (Zephyranthes sp.); umbrella sedges (Cyperus sp.)
  • wet-soil adapted houseplants and tropicals, i.e., peace lilies (Spathyphyllum sp.); dragon plant(?) (Hemigraphis sp.)
  • traditional aquarium plants, i.e., Anubias species; crypts (Cryptocoryne sp.); water hyssop (Bacopa sp.)

At present there are no vendors offering plant selections specifically for riparium culture, but one can accumulate plants for a composition with some research and careful shopping. If you already have a planted tank or two you might be able to acclimate some of your existing plants for riparium culture. Keep in mind that many aquatic plants which can grow both below the water’s surface (immersed) and with their foliage in the air (emmersed) develop distinct types of leaves for these two conditions. Each leaf type is physiologically adapted to its respective environment. In some plants the two leaf forms are quite distinct, such as mermaidweed (Proserpinaca palustris). The immersed foliage of this plant is finely divided and lacey, like carrot leaves, while the emmersed leaves are more compact with saw-toothed margins.

(Plant with two leaf forms)

Most Cryptocoryne species can be coaxed to develop emergent leaves by situating them with their crowns barely covered by the water surface. New leaves will be impelled to grow up into the air. A similar tack can be applied to stem plants, such as various Ludwigia, Hygrophila and Rotala. Some plants, especially larger Echinodorus swords will hurry to develop emmersed leaves if placed near the water’s surface. A few other plants, such as most Microsorum ferns and Anubias species, are truly amphibious. Provided that the the riparium air space is maintained very humid during their transition, the leathery leaves of these plants tolerate being taken directly from immered culture to an emmersed situation.

(crypt beginning emersed growth)

There are probably many tropical species grown as houseplants or greenhouse specimens that will work well for riparium culture. Some of these have already been widely applied in paludariums. Peace lilies, Spathyphyllum sp., are an especially promising group and I have had good luck with a couple of species. Ecological data seems to be scant for many kinds of houseplants, but some Spathyphyllum are described in scientific publications as using wet, shaded habitats in nature. Other aroid genera, such as Alocasia, Colocasia and Zantedeschia, also include potentially suitable species. Some of these grow very large, so look for the smaller species and varieities. A genus in the acanthus family, Hemigraphis, includes several easy-to-grow semi-aquatic species with attractive dark purple foliage that are frequently sold as houseplants.

A gradual root acclimation might be neccesary for plants transferred to traditional organic potting media to hanging planters. To make this transisition, clean all of the existing medium from the plant roots, then trim the roots back (consider saving this desription for “plant culture” article)


Several popular pond plants grow very well in paludariums. Many of these plants have robust, attractive foliage (i.e. Cyperus umbrella sedges) and/or showy flowers (i.e. Ruellia brittoniana). Look for the “marginals” selections to find the best possibilites for paludarium culture. It is advisable to choose tropical varieities instead of hardy pond plants because most members of the latter group require cool dormancy periods. A few tropical marginal bulbs, such as most Hymenocallis spider lilies, will go dormant, halting their growth and dropping their leaves. If rooted in hanging planters, however, such plants can be easily removed to a cooler, drier location for a few months. Size is another important consideration. Many pond plants grow to three feet high or taller, too large to display in an aquarium.


The shapes and growth habits of your plants come into play for an especially important effect in the planted riparium—visual depth. Since most of the plants are anchored along the rear pane of glass it is challenging to achieve visual depth: the composition will look distinctly two-dimensional if plants are merely lined up in their hanging planters. Be sure to select some species that can be encouraged to grow forward several inches into the middle-ground of the aquarium. Some grasslike plants, such as sweetflag (Acorus sp.) and giant hairgrass (Eleocharis montevidensis) have gently arching growth habits and are well-suited for creating visual depth. Semi-woody bushes, such as smartweed (Polygonum coccineum) can be trained such that their main stems grow out over the water’s surface, then branch out to fill the riparium midground with foliage. More limber stem plants can also do this if supported beneath by a Riparium Supplyfoam rafts.


Consider these factors together when planning combinations of plants in a whole composition. For example, plants that demand high humidity and grow well in low light, such as most Cryptocoryne, are ill-suited for combination with pond plants, which require more air circulation and brighter light. Careful species combinations is also relevant for the creation of riparium biotopes—representations of habitats in nature. Researching the flora and and fauna of wild habitats with trips to the field or published accounts while deciding upon biotope combinations of fish and plants is a challenging and fun way to learn more about the places where these organisms live.


Planting a riparium is a lot of fun. Especially where full-sized plants are used, the aquascape can develop a convincing, mature appearance quickly. Because they are supported by planters held in place with suction cups, one can reposition them easily to find the best composition or to create new variations later on.

Planting and plant care methods are treated in detail in the article, Plant Culture in the Riparium, but important points are reviewed here as well. A list of materials required for planting is provided below to review major points discussed in this article and to introduce riparium planting techniques:

  • aquarium enclosure & life support
  • substrates
  • live plants
  • Arroyo Aquatics Hanging Planters–enough to stretch across the width of the tank’s rear pane of glass; the hanging planter kit contains the following components:
    • plastic planter cups
    • heavy-duty vinyl suction cup
    • polyester planter screen
    • clay pellets
  • Trellis Raft kit:
  • Planter Substrate
  • liquidand/ or tablet plant fertilizers

To plant a specimen in a hanging planter, begin by inserting the planter screens, which will prevent the planter substrate from spilling through the holes in the container. The Medium Hanging Planter uses two screens, while the Small Hanging Planter uses just one along the rear inside surface. Pour in enough clay pebbles to cover the floor of the planter. These will also help to keep substrate in the planter, while also encouraging water circulation through the root zone. While holding the planter screens against the front and back of the planter with your fingertips, pour some planter substrate into the cup to fill it to about 1/3 full. This is a good time to add a tablet fertilizer if you plan to use such a product.

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3 Responses

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  1. Edinjapan says

    This is what I was looking for. These or similar products aren’t available here in Japan and I think they’d do well here.

  2. Hydrophyte says

    Ed, do you keep aquariums, and do you have a Website or other presence somewhere?

Continuing the Discussion

  1. How to Plant a Riparium linked to this post on August 4, 2009

    [...] will be final draft of Part #1 of two-part article, begun as draft in a previous post. 1-V-09 Cryptocoryne Riparium [...]