Tonina

Tonina fluviatilis, once the only species of its genus, has been reclassified by botanists as Paepalanthus fluviatilis, and the two names are used side by side in the hobby. It grows in slow blackwater rivers from Mexico to northern South America, forming dense mats in shallow water, and was brought into the hobby by Japanese aquascapers.

It is a specialist's plant, graded very difficult. It wants very soft water with a total hardness around 5 or less, an acidic substrate, and bright light, and CO₂ injection is effectively a must. A pH of 4 to 7 and temperatures of 18 to 29 °C keep it going, with a steady supply of iron and micronutrients while nitrate and phosphate never hit zero. Because it grows slowly, faster neighbours will shade and overgrow it, so it often gets a tank to itself beside Syngonanthus and Eriocaulon.

It grows upright with fine, light green leaves on slender stems to about 15 cm, and it is propagated by lateral shoots cut from the stem and replanted. Keep it where nothing can shade it and it forms a delicate, feathery stand.