Aquatic PlantsBeginner🌗 Medium light
Amazon frogbit
Limnobium laevigatum · also called South American spongeplant, Smooth frogbit, Common frogbit (Amazon)
Generally non-toxic to cats and dogs.
Amazon frogbit is a fast-growing floating plant with rounded, glossy leaves and long, trailing roots that provide cover and shade for surface-dwelling and shy fish. It is an excellent nutrient exporter, helping to outcompete nuisance algae in low-tech tanks.
Educational only. KinStation content is reviewed by licensed veterinarians but cannot replace an in-person exam. Always consult a licensed veterinarian or board-certified specialist for diagnosis, treatment, or any decision affecting your pet's health.
Quick facts
| Category | Aquatic Plants |
| Family | Hydrocharitaceae |
| Native origin | Central and South America (tropical Americas) |
| Care difficulty | Beginner |
| Light | Medium light |
| Pet toxicity | Pet-safe |
Light
Thrives under low to medium aquarium lighting; bright light produces compact, raised, spongy emergent leaves while dim light yields flatter, larger pads. Strong light plus high nutrients accelerates growth dramatically. As a floater it sits directly under the light source, so surface PAR is effectively high regardless of fixture strength.
Water
Tolerant of a wide range: temp 18-30 C (64-86 F), pH 6.0-7.5, soft to moderately hard water. Benefits from water-column dosing of nitrogen, phosphorus and especially iron and other micronutrients; iron deficiency shows as interveinal yellowing. Sensitive to surface salt buildup and prefers stable, nutrient-rich water. No CO2 injection needed.
Soil & potting
Not an epiphyte and not a rooted plant; it is a free floater that draws nutrients directly from the water column through its dangling roots, so no substrate is required. Do not plant or bury it; let it float freely. Trailing roots may be trimmed if they reach the substrate or tangle in equipment.
Environment — humidity, temperature, placement
No CO2 required as it accesses atmospheric CO2 at the surface. Prefers calm or gentle surface flow; strong current and water spray (filter outlets, surface skimmers) wet the leaf tops and cause rot. Grows emersed at the surface and is purely a floating plant. Keep surface agitation moderate to prevent crown rot; a partial lid that limits condensation dripping onto leaves helps.
Propagation
Spreads rapidly via daughter plants on short stolons (runners); separate plantlets once they develop their own roots. Can also flower and set seed at the surface. To control spread, scoop out excess mats regularly.
Toxicity detail
Non-toxic to fish, shrimp, snails and pets. However, Limnobium laevigatum is a recognized invasive aquatic weed and is regulated in parts of the US (e.g. listed/restricted in California and the southern states), Australia, New Zealand and parts of Europe; it can clog waterways. Check local regulations before purchase, never release it into the wild, and dispose of trimmings in the trash.
Growth stages
How this plant changes through its life — each stage often has its own care, diet and space needs.