How to Culture Copepods and Phytoplankton for Your Reef Tank

Mandarin dragonets, wrasses, and coral larvae all depend on tiny live prey that most hobbyists buy in expensive bottles. Establishing a home copepod phytoplankton culture reef keepers can draw from continuously saves money and guarantees a fresh, nutritious food source year-round. At Gensou Aquascaping, 5 Everton Park, Singapore, we maintain rolling cultures of both copepods and phytoplankton for our marine systems — and the process is far simpler than most hobbyists expect.

Why Culture Your Own

A single bottle of live copepods costs $15 to $25 SGD at local marine shops and may contain only a few hundred individuals, many of which get consumed by fish or sucked into filtration within days. Culturing at home produces thousands of copepods weekly from a single starter culture. Phytoplankton — the microscopic algae that feeds the copepods — doubles as a direct food for filter-feeding corals, clams, and tube worms. The two cultures form a self-sustaining food chain that, once established, costs almost nothing to maintain.

Starting a Phytoplankton Culture

Nannochloropsis oculata is the most forgiving phytoplankton species for beginners. Purchase a live starter from a local marine shop or online supplier. You will need a clear 2-litre plastic bottle, an airline with a rigid tube for aeration, a grow light or desk lamp providing 16 hours of illumination daily, and Guillard’s F/2 fertiliser concentrate. Fill the bottle with RO water mixed to 1.020 specific gravity using reef salt, add 1 ml of F/2 per litre, inoculate with 200 ml of starter culture, and provide constant gentle aeration. Within five to seven days in Singapore’s warm ambient temperatures, the water turns dense green.

Harvesting and Maintaining Phyto

Once the culture reaches a deep opaque green, harvest half the volume and replace it with fresh saltwater and fertiliser. This split-and-feed cycle keeps the culture in exponential growth. Run two or three bottles on staggered schedules so you always have a mature culture ready to harvest while younger bottles are growing. Store harvested phyto in the refrigerator for up to two weeks, shaking the bottle daily to keep cells in suspension. If a culture crashes — turning clear or brownish — discard it and restart from a clean bottle with fresh starter.

Copepod Culture Setup

Tigriopus californicus and Tisbe biminiensis are the two most commonly cultured species. Tigriopus are larger and hardier, making them ideal for feeding dragonets and wrasses. Tisbe are smaller and reproduce faster, better suited for seeding a refugium or feeding coral larvae. Set up a 5-litre container with saltwater at 1.024 specific gravity, gentle aeration, and no filtration — copepods need calm water and surfaces to graze on. A piece of plastic mesh or a wad of filter floss provides attachment sites for egg sacs.

Feeding Copepods

Add 50 to 100 ml of your phytoplankton culture to the copepod container every two to three days. The water should remain slightly green; if it clears completely within 24 hours, increase the phyto dose. Overfeeding phyto fouls the water — if you notice a film on the surface or the smell turns unpleasant, reduce the dose and perform a partial water change using fresh saltwater. At 28 to 30 degrees Celsius — typical in a Singapore home — copepods reproduce rapidly, with females producing new broods every four to six days.

Harvesting Copepods for Your Tank

Use a 100-micron mesh sieve to collect adult copepods from the culture container. Rinse them briefly in clean saltwater before adding to your display tank or refugium. Harvest no more than a third of the culture at a time to maintain a breeding population. For continuous supply, run two alternating culture containers and harvest from each on a weekly rotation. Target feeding in the evening when mandarin dragonets and other micropredators are most active.

Troubleshooting Common Issues

Contamination with rotifers or ciliates is the most frequent problem. If your copepod culture suddenly looks cloudy with swirling specks rather than crawling pods, a competing organism may have taken over. Start a fresh culture using isolated egg-bearing females picked out with a pipette. Phytoplankton crashes usually result from insufficient light, expired fertiliser, or temperature swings. Keep cultures away from direct sunlight and air conditioning vents. With a reliable copepod phytoplankton culture running, your reef gains access to the most natural and nutritious live food available — and your mandarin will never go hungry.

Related Reading

• Copepods in Aquariums: Identification and Should You Remove Them?
• Balling Method Explained: Three-Part Reef Dosing for Stable Chemistry
• How to Maintain Calcium and Alkalinity Stability in Your Reef Tank
• How to Plant HC Cuba From Tissue Culture: Separation and Spacing
• How to Culture Daphnia at Home for Your Aquarium