Hornwort (Ceratophyllum demersum)

Hornwort is a fast-growing submerged plant with bristly, feathery whorls, and it is about as close to unkillable as an aquatic plant gets. It has no true roots, so you can anchor it, wedge it between rocks, or simply let it drift, and it grows either way.

It is one of the two easiest plants to propagate that I know of. Pinch off a section, drop it in, and that section becomes a new plant. A single portion turns into a supply of it within a season.

For medaka this is a genuinely useful plant rather than just decoration. The dense growth gives fry somewhere to hide from the adults, it pulls nitrogen out of the water column, and it holds the biofilm that fry graze on between feedings.

You will receive a healthy starter portion. Grown outdoors in my own pots in North Carolina, alongside the fish.

Representative species photo. Your portion is cut fresh from my own pots at packing time.