Best Phytoplankton for Culturing Copepods

1. Green Algae (Nannochloropsis)

Best for: Day-to-day feeding, keeping cultures alive long-term
Looks like: Bright green powder or live green water
Why use it: Cheap, grows fast, packed with fats that keep copepods healthy. This is your "staple food."

Buy it as: Live cultures, frozen pastes, or freeze-dried powder labeled "Nanno" or "Green Water."

2. Golden Algae (Isochrysis or "T-ISO")

Best for: Making your fish healthier
Looks like: Golden-brown tint to the water
Why use it: Super high in DHA—the same omega-3 that makes salmon good for humans. Feed this 24–48 hours before feeding the copepods to your fish for maximum nutrition.

Buy it as: "Isochrysis," "Golden algae," or look for "High DHA" on the label.

3. Chain Diatoms (Chaetoceros)

Best for: Getting copepods to breed like crazy
Looks like: Microscopic chains (like tiny necklaces)
Why use it: Triggers egg production. If your culture is slowing down or the females aren't carrying eggs, add this.

Buy it as: "Chaeto" (not the big macroalgae—make sure it's the microalgae/powder form), "Shellfish Diet," or "Diatom blend."

Avoid: Regular Chlorella (the stuff in health food stores). Copepods can't digest the cell walls—they just poop it out green.

How to Feed (Without Overthinking It)

The "Tea Color" Method:

1. Add algae until the water looks like weak green tea or light apple juice

2. When it clears up (usually 1–2 days), add more

3. If the water looks like pea soup, you've added too much—dilute with fresh saltwater

Pro Tips:

• Small pods (newly hatched): They need the tiny green stuff (Nannochloropsis). It's like baby food.

• Big adult pods: They can handle larger algae like Tetraselmis or Thalassiosira.

• The 48-Hour Rule: If you're harvesting copepods to feed fish, give them a "golden algae boost" two days before. It’s like marinating chicken before you cook it.

Live vs. Powder: What Actually Matters

Budget hack: Most reef keepers do fine with a bottle of concentrated Nannochloropsis paste kept in the freezer and used a few drops at a time.

Quick Troubleshooting

"My copepods disappeared"
→ Probably starved. Water turned clear = empty plates. Feed more often.

"Water smells bad/looks milky"
→ Overfed. Bacteria are blooming. Do a water change and cut back on food.

"Copepods are alive but not breeding"
→ Add the chain diatoms (Chaetoceros) or golden algae. They're missing key vitamins for making eggs.

"My fish aren't growing well on these pods"
→ You're not "gut-loading" them. Feed the copepods golden algae (Isochrysis) for 2 days before feeding them to fish.

Bottom Line

Don't use just one food. Buy a green algae base (Nannochloropsis) and rotate in golden algae (Isochrysis) once a week. If you want baby copepods everywhere, add some chain diatoms. Keep the water lightly tinted, not swampy, and you'll have more pods than you know what to do with.