Sweet potato (Ipomoea batatas) is a surprisingly versatile and rewarding plant to grow in an aquatic setup. It is not a true aquatic plant, but it thrives as an emersed or semi-aquatic plant, meaning the roots and lower vine stay submerged while the foliage grows above the waterline.

How it works

Sweet potato is grown as a hanging or trailing vine over the aquarium or pond. The roots are submerged in the water, where they absorb nutrients directly, acting as a natural filter. The leaves and vines grow out of the tank and trail or climb above the surface.

Why aquarists love it

• Nutrient export is one of the biggest benefits. The plant aggressively absorbs nitrates, phosphates, and ammonia from the water, helping keep the tank clean and reducing algae.
• It grows extremely fast, which means it pulls nutrients out of the water quickly and continuously.
• It is low cost and easy to source. A single sweet potato from a grocery store can get you started.
• It adds a lush, tropical aesthetic with large heart-shaped or lobed leaves trailing over the tank.

Getting Started

What you need

• One organic sweet potato (avoid non-organic if possible, as some are treated with sprout inhibitors)
• Toothpicks or a small basket/net cup
• An aquarium with open top or a hang-on setup

Identifying which end goes in the water

Sweet potatoes have two distinct ends and it matters which one you submerge.

• The root end is the end that goes in the water. It is typically the narrower, more tapered end and may already show small fibrous root nubs or slight wrinkling
• The stem end is the end that stays above water. It is usually the broader, blunter end and is where the sprouts and leaves will emerge
• If you are unsure, look for any tiny existing buds or eyes on the surface. Buds tend to cluster more toward the stem end, which should face up
• When in doubt, place the potato horizontally in water for a few days and observe which end begins sprouting upward and which begins rooting downward, then reorient accordingly

Sprouting the potato

1. Suspend the sweet potato halfway in a glass of water using toothpicks, with the bottom half submerged
2. Place in a warm, bright spot
3. Sprouts and roots will appear within 1 to 3 weeks
4. Once roots are several inches long, it is ready for the aquarium

Placing it in the tank

• Rest or hang the potato so the roots dangle into the water and the sprouting top stays above the waterline
• You can use a net cup or small basket tucked into the rim of the tank
• Alternatively, cut a vine cutting and simply drape the cut end into the water, roots will develop quickly

Light Requirements

The foliage above the tank needs good light. A bright window or a grow light works well. The submerged roots do not need light.

Water Conditions

Sweet potato roots are tolerant of a wide range of water conditions.

• Temperature: 65 to 82 degrees F (it prefers warmer water, which aligns well with tropical fish tanks)
• pH: 6.0 to 7.5
• It tolerates both freshwater community tanks and planted tanks well

Maintenance Tips

• Trim vines regularly to encourage bushy growth and continued nutrient uptake
• Remove any leaves or stems that fall into the water to prevent rot
• If the potato itself begins to rot in the water, remove it and continue with the rooted cuttings
• You can propagate endlessly by snipping vine cuttings and placing them in water.
• Make the plants removal and replacement as possible for periodic cleaning of the ponds and tanks

Best matches for fish compatibility

• Cichlids and other fish that uproot plants, since the sweet potato is above the waterline
• High-nutrient tanks or tanks with heavy bioloads, where nitrate export is especially valuable
• Shrimp tanks, as the fine roots provide excellent grazing and hiding surfaces for shrimp and fry
• Koi are omnivores and enthusiastic foragers. They will absolutely nibble, pull, and eventually destroy the submerged roots. Either think of the sweet potatoes as a supplemental food source and partially protect them or plan full protective measures.
• Sweet potato is safe for koi to consume. The roots, vines, and leaves are not harmful. So while koi may damage the plant, they will not be harmed by eating it.
• Large koi are strong fish. They can dislodge or knock around anything near the waterline, including net cups or baskets holding the potato in place. A secure mounting method matters more with koi than with smaller fish.

Cautions

• It is not a fully submerged plant. Do not try to grow it fully underwater as it will rot
• In very low-light indoor spaces, the foliage may become leggy and pale
• It will not survive freezing temperatures if you move it outdoors seasonally in MN, so keep it as an indoor plant year-round or treat it as seasonal

It is a wonderfully practical and beautiful addition to any aquarium setup, especially if you enjoy blending function with a natural, living aesthetic.

©2026 Suzy Mottet bloomhearty.com writing, creation, and design