Live ostracods: essential micro-cleaners for natural aquariums and low-tech ponds
What is an ostracod?
Ostracods are tiny crustaceans (0.5 to 1 mm) protected by a bivalve shell that resembles a small “bean grain.” Depending on the species, they move across the substrate or swim briefly, cleaning up microalgae, organic particles, and biofilm by eating them. If leftover food or a carcass is lying around, they rush over and consume it. Even shrimp molts or daphnia suit them!
Present on Earth for more than 400 million years, they form the first animal link in the aquatic food chain and naturally stabilize the nitrogen cycle in any planted tank or natural outdoor aquarium.
Very closely related to daphnia, they feed on walls and surfaces, whereas daphnia eat particles, algae, and bacteria suspended in the water.
We offer two different ostracod species, one strictly walking (brown) and the other swimming (orange).
Why introduce ostracods?
- Continuous purification: transform microscopic waste into nutrients immediately available to plants.
- Complete biological cycle: fill the “living filter” stage in an aquarium without a pump, a key stage of biological cycles that is often missing in aquariums.
- Self-regulating population: multiply only when food is abundant.
- Useful biodiversity: provide a varied microbiota beneficial to fish, snails, and shrimp, and especially to the entire aquarium or pond ecosystem, stabilizing and balancing it through biodiversity.
- Food reserve: as edible organisms, they provide fish with a natural snack during food shortages, since they are generally less appealing than other live foods.
Introduction and maintenance tips
- 🏠 Simply pour the culture of 30 ostracods into the destination tank, after first carrying out basic acclimatization: equalize the temperatures and gradually exchange the water.
- 🌙 Choose a quiet area or dusk so they can settle in. You can also use the open section of the filter chamber to install them safely away from fish, if there are any.
- 🍽️ No dedicated feeding: tank waste and biofilm are sufficient for them, so feeding them would serve no purpose.
- 🔍 Observe their reproduction: still poorly understood, their reproduction is collective, with many individuals laying and tending eggs arranged in “plaques” on the glass or various surfaces. These plaques range from brown to bright orange and often contain hundreds of eggs. Keep a magnifying glass next to the aquarium!
- 🌡️ Ideal temperature: 10 - 28 °C, but they tolerate much lower temperatures (they survive the harshest winters outdoors) or higher temperatures (they are very active during heatwaves).
- ⚡ Avoid powerful pumps: especially for the swimming species (yellow), as the ostracods could be sucked into the filter.
FAQ - Ostracods in natural aquariums and ponds
Are ostracods dangerous for fish?
No. They are neither parasites nor predators. They are completely peaceful and too small to injure or stress your aquatic residents. In fact, fish are more likely to eat the ostracods!
Can they proliferate excessively?
Their numbers strictly follow the amount of available waste; in a well-maintained tank, they remain unobtrusive. They proliferate only in environments where no other species can live (heat, total anoxia, bacterial overgrowth, etc.).
Will they make the water cloudy?
On the contrary: by filtering biofilm and microparticles, they help clarify the water. As for green water, they do not filter it, unlike daphnia. However, they eat the microscopic algae that make it up as those algae gradually settle on the bottom.
Can they live outdoors in a pond?
Yes, as long as the water does not freeze completely. They tolerate seasonal variations perfectly and simply need some liquid water to remain unfrozen.
Do they require special filtration or oxygenation?
Not necessary. They thrive perfectly in a planted low-tech environment without any additional equipment.
Additional information
Species: we raise and offer a yellow swimming species and a brown walking species. They complement each other.
Packaging: batch of approximately 30 individuals (indicative weight: 12 g)
Guarantee: raised without any chemical treatment, entirely naturally, with no direct or indirect contact with fish. No collection from the wild.
Recommendation: as a matter of principle and precaution, please never release these organisms into the wild.
