Water Hyacinth

Water Hyacinth is the most recognisable floating plant in the world, but it carries a reputation that every aquarist should know before adding it to a tank. In many regions it is classified as an invasive species: under warm, nutrient-rich conditions it doubles its biomass in under two weeks and can choke entire waterways. Keeping it in an indoor aquarium is generally safe, but never release it into local ponds or streams. The plant produces thick, glossy rounded leaves on inflated petioles that act as floats, with a showy lavender flower spike that emerges above the water line under strong light. Flowgrow gives an optimum temperature of 25 to 30 °C and pH from 5 to 8, with high light preferred for compact growth and flowering. Carbon dioxide is not required — water hyacinth takes what it needs from the air — but nitrate and phosphate levels should be kept in the typical 10–50 mg/l and 0.1–3 mg/l ranges to avoid deficiency. The long, feathery roots provide shelter for fry and absorb excess nutrients, making it a practical addition to fry-rearing or heavily stocked tanks. The difficulty rating on Flowgrow is difficult, not because the plant is hard to keep alive — it is almost impossible to kill — but because controlling its explosive growth in an open-topped tank requires consistent thinning. Without regular pruning it blocks light from everything below.