How to culture copepods at home

What you need

Gather everything before you start. A clean, prepared workspace is the single biggest factor in a successful first culture. If you purchased the Complete Edition of the Copepod Culture Kit, your air pump, airline tubing, and control valve are included. The Lite Edition assumes you already have aeration equipment to hand.

• Clean culture vessel (the 4L container included in your kit, or a small aquarium)
• Air pump with airline tubing
• Control valve or clamp to regulate airflow
• Drip loop and check valve for airline safety
• Cover for the container (allows air exchange, prevents contamination)
• Clean synthetic seawater mixed to 35 ppt (1.025 specific gravity)
• Reefphyto Copepod Feed (included in kit)
• Turkey baster or pipette for debris removal
• Copepod sieve for harvesting

Setting up your culture vessel

The initial setup takes about 20 minutes. Take your time here because the conditions you create now determine how well your culture establishes over the coming weeks.

1. Prepare the vessel. Rinse your culture container thoroughly with warm fresh water. Do not use soap, detergent, or any chemical cleaning agent. Even trace residue is harmful to copepods. If the container has been used before, a thorough rinse with hot fresh water is sufficient.
2. Add saltwater. Fill the container between half and two-thirds full with your pre-mixed synthetic seawater at 35 ppt. Leaving space at the top reduces the risk of overflow and gives the culture room to breathe.
3. Install aeration. Attach your airline tubing to the air pump. Install a drip loop (a U-shaped dip in the tubing below the pump level) and a check valve to prevent water back-siphoning into the pump during a power cut. Place the open end of the tubing near the bottom of the container. Do not use an airstone. Gentle bubbles directly from the tubing are ideal for copepods.
4. Set the airflow. Use the control valve to regulate the air to 1 to 3 bubbles per second. This is much gentler than most people expect. Copepods need water movement and oxygenation, but strong flow exhausts them and can damage egg sacs. If in doubt, go gentler.
5. Cover the container. Place a loose-fitting cover over the top. This prevents dust, debris, and airborne contamination from entering the culture while still allowing gas exchange. A piece of fine mesh, a loose lid, or cling film with several holes punched in it all work well.
6. Add your copepods. Gently pour your live Tigriopus californicus starter culture into the prepared vessel. Do not acclimatise by floating the bag first. Tigriopus is an extremely robust species and handles direct introduction well, provided the salinity is within range. Place the vessel at stable room temperature, away from direct sunlight and heating or cooling sources. A shelf, countertop, or utility room works well. Copepods do not need supplemental lighting - indirect ambient light is sufficient.

Feeding your culture

Feeding is the single most important factor in copepod culture success, and overfeeding is the single most common cause of failure. The approach is simple once you understand the visual cues, but it requires patience in the early days.

How to feed

Add Reefphyto Copepod Feed to the culture water until it reaches the colour of a Granny Smith apple skin. That is a light, slightly cloudy green. The water should be opaque enough that you cannot clearly see through the container to the other side, but not so dark that you cannot see the copepods moving within it.

Once you have reached that colour, stop. The copepods will graze on the microalgae suspended in the water over the next one to three days, gradually clearing it. When the water begins to clear and you can see through it again, it is time to feed once more.

Feeding in the first week

In the first week after setup, feed at roughly half the rate you think is necessary. Your copepod population is small at this stage and cannot process as much food. A faint green tint is plenty. As the population grows over the following weeks, you will notice the water clears more quickly, which is your signal that the culture is consuming more and is ready for slightly larger feeds.

What you are feeding

Reefphyto Copepod Feed is a concentrated blend of four live microalgae species selected specifically for harpacticoid copepod nutrition and reproduction. It provides the essential fatty acids, proteins, and carotenoids that Tigriopus californicus needs to breed consistently. Store the feed in the refrigerator between uses and shake well before each dose.

Target water parameters

Tigriopus californicus is one of the most tolerant marine organisms you will encounter, which is one of the reasons it is the ideal species for home culture. That said, stability matters more than perfection. Sudden swings in salinity or temperature are far more dangerous than slightly imperfect but consistent conditions.

Maintenance schedule

Copepod cultures are low-maintenance once established. The daily time commitment is under two minutes. Here is what a typical routine looks like.

Harvesting

Once your culture is established and visibly dense with active copepods (typically four to six weeks after setup), you can begin harvesting to feed your reef or stock your refugium.

How to harvest

Pour a portion of the culture through a fine copepod sieve. The sieve catches the copepods while the culture water passes through. Rinse the sieve gently with clean saltwater, then tip the copepods into your tank, sump, or refugium. Replace the harvested volume with fresh pre-mixed saltwater at the same temperature and salinity.

How much to take

Never harvest more than 25 to 30 percent of the culture volume at one time. Taking too much slows recovery and can destabilise a young culture. Leave at least seven to ten days between harvests to allow the population to bounce back. As your culture matures and becomes denser, you will find it recovers more quickly and you can harvest more frequently.

Building a refugium population

If your goal is to establish a self-sustaining copepod population in your refugium rather than direct feeding, introduce harvested copepods into the refugium with the lights off. The animals will distribute themselves naturally and begin colonising available surfaces. Regular small additions over several weeks build a stronger founding population than a single large dump.

What to expect

Understanding the normal growth cycle prevents unnecessary worry during the early weeks when things may seem slow.

Weeks 1 to 2

Your starter population is settling in. You will see adults moving around the vessel, but numbers will not visibly increase yet. This is completely normal. The copepods are acclimatising, feeding, and beginning to reproduce. Females will start carrying egg sacs within a few days of introduction. Do not increase feeding to try to speed things up.

Weeks 3 to 4

You should start noticing more activity. Tiny nauplii (larvae) become visible as white specks moving through the water. The culture water may clear slightly faster between feeds as the growing population consumes more food. This is a good sign.

Weeks 4 to 6

Population density increases noticeably. You will see copepods of all sizes, from adults to nauplii, throughout the water column and on the container walls. The culture clears food significantly faster. This is when you can begin your first harvest.

Week 6 onwards

A mature, well-maintained culture will sustain regular harvesting indefinitely. Many keepers run the same culture for months or even years with nothing more than regular feeding, occasional water changes, and periodic harvesting.

Troubleshooting

If your culture has crashed, the water has turned cloudy or white, numbers are declining, or something just does not look right, head to our dedicated troubleshooting centre. It covers every common copepod culture problem with step-by-step guidance on how to fix it.

If you cannot find the answer there, contact me directly. I am happy to troubleshoot culture issues personally and help you get back on track.