Daphnia Magna
Live Daphnia Magna Cultures
Science-Backed. Wisconsin-Grown. Veteran-Owned.
There is no substitute for live food in the aquarium hobby. No frozen cube, no freeze-dried wafer, no processed pellet delivers what a living organism delivers the moment it enters your tank: natural hunting behavior, triggered feeding response, fully intact fatty acids, active enzymes, and Vitamin C that has not been oxidized away in processing.
Daphnia magna — the water flea — has been a cornerstone of the live food tradition for as long as serious fish keepers have been serious about fish breeding.
Meet Daphnia Magna
Daphnia magna is a freshwater crustacean in the order Cladocera — more closely related to shrimp and crayfish than to any insect. Adults reach 1.5–5.0 mm, making D. magna the largest of the common culture daphnids. That size is a feature: adults are visible to fish with any vision whatsoever, and a gravid female carrying a full brood chamber is an unmistakable meal. Lifespan is 40–56 days under good culture conditions; a single female can produce 6–22 clutches of eggs in her lifetime.
Exceptional Nutritional Profile
Daphnia passes through your fish with two advantages over any processed food: it is alive when it enters the water, and it is whole when it is eaten.
| Nutrient | Daphnia magna | Comparison |
|---|---|---|
| Crude protein | 50–67% | Fish meal: 65–72% |
| Crude lipid | 15–25% | Bloodworms: 5–10% |
| Phospholipids | 30–40% of lipid fraction | Most processed: <5% |
| Carotenoids | Present (beta-carotene) | Absent in most processed food |
| Vitamin C | 20–50 mg/100g DW | Destroyed in drying/processing |
Why phospholipids matter: Fish larvae cannot synthesize phospholipids from dietary triglycerides at the rates their development demands. Phospholipid-rich live food supports gut membrane development, eye development, and early growth in a way no dry diet achieves.
The gut-loading advantage: Every SC culture is gut-loaded for 48 hours on log-phase Chlorella vulgaris before harvest. When your fish eat them, they receive the Daphnia's own nutrition plus an intact bolus of Chlorella — a double dose of live nutrition.
Which Fish Love Daphnia Magna?
| Fish type | Suitability | Notes |
|---|---|---|
| Bettas | ★★★★★ Excellent | Adults love the chase; triggers breeding response |
| Goldfish & koi | ★★★★★ Excellent | High volume feeder; excellent natural food |
| Killifish | ★★★★★ Excellent | Traditional conditioning food for spawning |
| Rainbowfish | ★★★★★ Excellent | Very enthusiastic feeders |
| Cichlids (medium+) | ★★★★☆ Very good | Excellent conditioning food |
| Livebearers | ★★★★☆ Very good | Guppies, mollies, swordtails thrive |
| Discus | ★★★★☆ Very good | High-protein conditioning; pairs well with Moina |
| Tetras (smaller) | ★★★☆☆ Good | Smaller tetras prefer neonates or Moina |
| Fry (all species) | Use Moina instead | Moina neonates are the correct size for first-feeding fry |
Seasonal Production — Wisconsin Summer
Daphnia magna is a temperate species that thrives in outdoor summer production. In Wisconsin, our outdoor season runs May 15 through September 30. Outdoor 20-gallon Rubbermaid cultures in direct sun reach 3–5× the density of indoor cultures — free yield from free sunlight. Every SC culture traces back to these outdoor production rotations during the warm season.
What We Ship
Every culture ships in a reusable food-grade container on a Monday–Wednesday schedule. Your container is your starter culture vessel. No immediate transfer needed — connect an airstone, place near a window, and feed Chlorella. Animals are typically ready to harvest within 24–48 hours of arrival.
Our Daphnia Starter Kit includes a live culture, our 20-page care guide, food mix, and pipette — everything needed to start a home culture from day one.
Part of the Three-Organism System
Daphnia magna covers the medium-to-large fish size range (1.5–5 mm). Paired with Moina macrocopa for fry and small fish, and Chlorella vulgaris as the nutritional foundation, the complete three-organism system covers every fish from first-feeding fry through large adult cichlids with no size gap.
Browse all Daphnia cultures →
Starter kits & bundles →
Learn about the complete live food system →