How to culture rotifers at home

What you need

Rotifers are surprisingly hardy organisms when the basics are right, but getting your workspace prepared before you start makes a real difference to how smoothly your first culture establishes. Gather everything listed below before you open your starter culture.

• Culture container (included in your kit - 4L, 10L, or 20L depending on edition)
• Air pump with airline tubing
• Adjustable air control valve
• Drip loop and check valve for airline safety
• Cover for the container (allows air exchange, prevents contamination)
• Clean synthetic seawater at 1.019 - 1.021 specific gravity
• Reefphyto Rotifer Feed (included in kit)
• Fine mesh filter (included in kit, for harvesting)
• Turkey baster or pipette for debris removal (optional)

Setting up your culture vessel

The initial setup takes about 15 minutes. Rotifers are more forgiving than many people expect, but clean equipment and correct salinity from the start will save you problems later.

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 lethal to rotifers. If reusing a container, a thorough rinse with hot fresh water followed by air drying is sufficient.
2. Add saltwater. Fill the container approximately two-thirds full with clean synthetic seawater at a specific gravity of 1.019 to 1.021. This is lower than reef tank salinity and is important for optimal rotifer reproduction. Allow the water to reach room temperature before adding your culture.
3. Install aeration. Attach your airline tubing to the air pump. Install a drip loop and check valve to prevent water back-siphoning during a power cut. Position the open end of the tubing near the bottom of the container. Gentle, steady bubbling is what you are aiming for.
4. Add initial feed. Add Reefphyto Rotifer Feed to the water until it reaches a leafy green colour, similar to the colour of spinach or kale leaves. This provides immediate nutrition for your rotifers the moment they are introduced.
5. Introduce your rotifers. Gently pour your live Brachionus plicatilis starter culture into the prepared vessel. The rotifers will begin dispersing through the water column within minutes.
6. Cover and position. Place a loose-fitting cover over the container and position it at stable room temperature, away from direct sunlight and away from heating or cooling sources. Rotifers do not need supplemental lighting. Ambient room light is sufficient.

Feeding your culture

Rotifers feed continuously. Unlike copepods, which graze and then rest, rotifers are constantly filtering particles from the water. This means maintaining a consistent food supply is essential for a productive culture.

The visual cue

Your guide to feeding is colour. The culture water should always maintain a leafy green colour, like spinach or kale leaves. When the water begins to clear and lighten, it means the rotifers have consumed most of the available food and need more. Add Reefphyto Rotifer Feed in small amounts until the leafy green colour is restored.

How often to check

Check the water colour once or twice daily. In the first week, the culture will consume feed slowly because the population is still small. As the population grows, you will notice the water clearing faster between feeds. A culture that took two days to clear initially may clear in 12 hours once fully established. Adjust your feeding frequency to match.

What you are feeding

Reefphyto Rotifer Feed is a concentrated blend of Nannochloropsis oculata and Tetraselmis suecica, two microalgae species selected specifically for Brachionus plicatilis nutrition. It provides the proteins, lipids, and fatty acids that rotifers need to reproduce rapidly. Store the feed in the refrigerator between uses and shake well before each dose.

Target water parameters

Brachionus plicatilis is a hardy rotifer species that tolerates a range of conditions, but stability and correct salinity are the two most important factors. The lower salinity range is particularly important - rotifers reproduce significantly faster at 1.019 to 1.021 than at reef tank salinity.

Maintenance schedule

Rotifer cultures need slightly more active maintenance than copepod cultures because rotifers produce more waste relative to their body size. The key routine is a fortnightly deep clean, with daily feeding checks in between.

Harvesting

Once your culture is visibly dense with active rotifers swimming throughout the water column (typically five to seven days after setup), you can begin harvesting. Rotifer cultures recover faster than copepod cultures, so daily harvesting is possible once the population is established.

How to harvest

Pour a portion of the culture water through the fine mesh filter included in your kit. The mesh catches the rotifers while the culture water passes through. Rinse the collected rotifers briefly with clean seawater to remove excess feed, then add them to your tank or larval rearing vessel. Discard the strained water - do not pour it back into the culture, as it contains waste products.

How much to take

Remove no more than 25 to 30 percent of the total culture volume per harvest. Immediately replace the removed volume with fresh synthetic seawater at the correct salinity and add feed to restore the leafy green colour. With proper feeding, the culture will rebuild its population within 24 hours.

Enrichment before feeding

For maximum nutritional value when feeding fish larvae or corals, you can enrich your rotifers with live phytoplankton or a dedicated enrichment product two to four hours before harvesting. This dramatically increases their fatty acid content and improves survival rates in larval fish. Rinse enriched rotifers before feeding to remove excess enrichment product.

What to expect

Rotifers reproduce faster than copepods, so you will see results sooner. Here is what a typical culture progression looks like.

Days 1 to 3

Your starter population is settling in and beginning to feed. You will see rotifers swimming in the water column if you look closely. The water will remain green from the feed. Do not increase feeding or disturb the culture during this period.

Days 3 to 5

The population is reproducing. You may notice the water clearing slightly faster between feeds as more rotifers are consuming the available food. This is a good sign. Begin feeding a little more frequently to keep up with demand.

Days 5 to 7

The culture should be visibly dense. You will see rotifers throughout the water column, particularly when you hold the container up to the light. The water may clear noticeably between feeds. You can begin your first harvest at this stage.

Week 2 onwards

A mature rotifer culture in good condition can support daily harvesting indefinitely, provided you maintain the feeding and fortnightly maintenance routine. Many keepers run the same culture for months with nothing more than regular feeding, water changes, and consistent care.

Holiday care - up to 7 days

If you need to leave your culture unattended for up to a week, you can preserve a backup portion in the refrigerator. The cold temperature slows rotifer metabolism dramatically, allowing them to survive without fresh feed for several days.

Before you leave

Transfer approximately one litre of your established culture to a clean, smaller container such as a plastic bottle or jar. Add extra Reefphyto Rotifer Feed until the water is noticeably darker green than usual - this provides a food reserve. Place a loose cover on the container (do not seal it airtight - rotifers still need some gas exchange) and store it in the refrigerator at 4 to 8 degrees Celsius.

When you return

Remove the backup from the refrigerator and allow it to warm gradually to room temperature over two to three hours. Check for living, swimming rotifers. They may be sluggish at first but should become active as the water warms. Use this backup as your new starter culture, following the initial setup steps in a clean container with fresh seawater, proper aeration, and feeding. Allow three to five days for the culture to rebuild to full density.

Troubleshooting

If your culture has crashed, the water smells foul, the rotifers are not swimming actively, or you suspect contamination, head to our dedicated troubleshooting centre. It covers every common rotifer 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.