GEMMA Micro by Skretting is the gold standard dry feed for zebrafish (Danio rerio) in research facilities worldwide. Formulated with hydrolyzed marine proteins, HUFAs, phospholipids, and algae, it provides complete nutrition across all developmental stages — from first feeding at 5 days post-fertilization through adulthood.
But choosing the right particle size at the right time is critical. Feed too large and larvae can't ingest it. Feed too small to adults and you waste product. This guide breaks down exactly which Gemma Micro to use, when to transition, and how much to feed.
Nutritional Composition
All four Gemma Micro sizes share the same nutritional composition — the only difference is particle size. This makes transitions seamless, as the nutritional profile remains constant throughout development.
Detailed Feeding Protocol
Stage 1: First Feeding (5-17 dpf) — GEMMA Micro 75
Begin feeding GEMMA Micro 75 at 5 days post-fertilization, when zebrafish larvae have fully absorbed their yolk sac and begin exogenous feeding. The 50-100 µm particle size is small enough for the tiny larval mouth.
Feeding regime: Feed ad libitum at least 3 times daily. Distribute feed evenly across the water surface. Remove uneaten feed to maintain water quality. Many facilities supplement with live rotifers during this stage for improved growth and survival.
Stage 2: Juvenile Growth (18-30 dpf) — GEMMA Micro 150
Transition to GEMMA Micro 150 at approximately 18 dpf, when fish are large enough to ingest 100-200 µm particles. Continue feeding 3 times daily ad libitum. This is a rapid growth phase — adequate nutrition is critical.
Stage 3: Sub-adult to Adult (31+ dpf) — GEMMA Micro 300
GEMMA Micro 300 (200-500 µm) is the most commonly used size in adult zebrafish facilities. It has been documented to improve fecundity and allows reducing feeding frequency to twice daily for sub-adults and once daily for adults and spawners.
Stage 4: Adult Spawners (optional) — GEMMA Micro 500
Some programs transition to GEMMA Micro 500 (400-700 µm) during the adult stage, particularly for breeding fish. The larger particle size means less waste per feeding event. Feed once daily.
Pricing & Packaging
| Product | Particle Size | Packaging | Price (HT) |
|---|---|---|---|
| GEMMA Micro 75 | 50-100 µm | 0.5 kg | €145.60 |
| GEMMA Micro 150 | 100-200 µm | 0.5 kg | €100.19 |
| GEMMA Micro 300 | 200-500 µm | 0.5 kg | €80.03 |
| GEMMA Micro 300 | 200-500 µm | 2.5 kg | €349.98 |
| GEMMA Micro 500 | 400-700 µm | 2.5 kg | €276.51 |
GEMMA Micro — All Granulometries
Select your size at checkout. Non-GMO, 59% protein. Planktovie is the official European distributor of Skretting zebrafish feeds.
Storage & Shelf Life
GEMMA Micro should be stored in a cool (<20°C), dark, dry place. The shelf life is 24 months from the date of manufacture when unopened. Once opened, use within 1 month — keep the bag sealed and refrigerated to maintain nutritional integrity.
GEMMA Micro is packaged in special aluminum/polyethylene bags under modified atmospheric conditions to preserve freshness and prevent oxidation of the sensitive fatty acids.
Supplementing with Live Feed
While GEMMA Micro provides complete nutrition as a standalone diet, many facilities achieve better growth and survival by supplementing with live feed during early development:
- Rotifers (5-20 dpf) — L-type Brachionus plicatilis cultured with RGcomplete. See our rotifer culture guide.
- Artemia nauplii (10-30 dpf) — Freshly hatched from Micro Artemia Cysts or GSL Artemia Cysts.
- Daphnia magna (20+ dpf) — Live freshwater cladocerans, 2-3 times per week for adults.