Live water lice: natural cleaners for a balanced aquarium
What is a water louse?
The water louse (Asellus aquaticus) is a freshwater detritivore crustacean, close to the terrestrial woodlouse. Usually measuring 5 to 10 mm, it lives on the ground or under leaves to decompose food remains, algae, and plant debris. Discreet and harmless to fish, shrimp, and plants, it plays a key role in the biological balance of any low tech aquarium and obviously any pond or natural aquatic ecosystem. It reproduces very well, perfectly withstands winter outdoors, and watching it is truly fascinating!
Why add water lice to a natural aquarium?
- Continuous biological cleaning: daily eliminate dead leaves, biofilm, and various waste without human intervention.
- Constant activity: watching their behavior, movements, and reproduction is fascinating: they are the largest animals of the micro-fauna, related to shrimp.
- Nutrient cycle: transform organic matter into nutrients absorbed by plants. They provide the often missing link in aquariums between organic waste and bacteria.
- Living micro-fauna: the smallest are a natural food source for adult fish.
- Low tech natural cleaner: ideal in a filterless aquarium where natural cycles are relied upon without technology.
Compatibility and living conditions
- 🏠 Planted tanks, nano-aquariums, trash bins, aquariums without filters and obviously ponds and mini-ponds of all sizes.
- 🤝 Coexist peacefully with snails, shrimp, non-predatory fish.
- 🌡️ Temperature: 2 - 30 °C, you can see them running under the ice in winter in ponds!
- 💧 Water: Prefer water with non-zero hardness (tap water is perfect), though it is not essential.
- 🍃 Prefer a bottom covered with dead leaves (in a pond for example), alder cones or roots to hide. Lawn-like plants such as dwarf Sagittaria, Littorella, or Java moss are also welcome and they will make their home there. In the pond, they will be the queens of the bottom sludge!
- ⚠️ Sensitive to heavy metals and pollution: their presence indicates healthy water, they are a bio-indicator species.
Usage tips
- 🌡️ Proceed with acclimation: equalize temperatures, open the bag to give them oxygen again, transition from one water to another in stages.
- 🌙 Introduce the batch of Water lice into the tank, preferably in the evening (especially if fish are present). This will give them time to hide.
- 📦 Do not try to separate them from the white support on which they traveled: their legs are fragile and they will come out by themselves when they feel safe enough. You will then just need to remove the support once abandoned by the Water lice.
- 🏠 Provide hiding places (leaves, stones, mosses, turf plants) and avoid voracious predators (botia, large cichlids...).
- 🍽️ No specific feeding: Water lice consume existing waste and clean plants of dead tissue and algae.
- 👥 Self-regulated population: they reproduce slowly in batches, without visually invading the tank.
- ❄️ In pond filters, they devour trapped leaves and improve water circulation. They remain fully active in winter and reproduce mainly between February and April.
FAQ - Water lice for aquarium and pond
Can they escape?
No, they live fully submerged and breathe underwater.
Are they visible?
More at night; during the day they tend to stay hidden. However, you can observe formed pairs and females carrying eggs.
Are they likely to proliferate?
Their reproduction is slow and follows the amount of available waste.
Compatible with bare tank (without substrate)?
Yes, but soil increases their efficiency and comfort.
Do they tolerate outdoor conditions?
Yes, in a shaded trashcan terrarium without large predatory fish and of course in a pond or a mini-pool.
My large individuals are dying...
This is normal. The largest individuals are males, and they reproduce after their last molt. Then they die quickly (a bit like salmon). Adult females also die, but they survive long enough to carry their young.
Additional information
Scientific name: Asellus aquaticus
Packaging: batch of 10 Water lice on a neutral travel support (indicative weight: 26 g)
Guarantee: raised in France, without chemical treatment or contact with fish, in completely natural conditions. No collection from the wild.
Recommendation: as a principle and precautionary measure, I ask you never to release these organisms into the wild without verifying that the species is naturally present in the concerned ecosystem.
