Amplifeed Replete Instructions for Use

Sustainable Nutrition’s Amplifeed Replete

Rotifer Feed, Rotifer and Artemia Enrichment

Amplifeed Replete is a fine powder (95% by volume that is milled to less than 10µm in size to match the rotifer mouth gape) that is excellent as a rotifer feed and rotifer and Artemia enrichment. The rich nutritional profile of Amplifeed Replete not only produces stable, consistent rotifer cultures, Rotifers fed Amplifeed Replete have larger mass, more eggs, and are more nutritious than algae fed rotifers. Moreover, predators that consume Amplifeed fed rotifers or Artemia benefit from this enriched, nutrient-dense food, which enhances their survival, growth, health, and color.

There are generally two ways of culturing rotifers: batch closed systems and flow through systems. If Sustainable Nutrition was near a source of clean sea water, we would absolutely use a flow through system. However, in Tennessee we are about 1000 km from the sea, so we use a closed batch system that includes live algae. More about this below.

Flow through system: Brachionid rotifers are about 250 µM long and indiscriminate filter feeders. They have relatively small mouths, so they can only ingest particles less than about 10 µM in diameter, which in nature is mostly live algae cells. A milling process patented by Sustainable Nutrition allows us to produce an exceptional rotifer feed of the appropriate size for rotifers to easily ingest. Rotifers fed Amplifeed Replete have higher metabolic activity, egg production, and generally grow to higher densities than rotifers fed only algae. A consequence is that they produce a lot of metabolites that could accumulate and cause toxicity. Culturing rotifers in a flow through system enables the maintenance of high-water quality while feeding abundant amounts of Amplifeed Replete and producing high densities of rotifers.

 “Algae paste” rotifer feeds suffer from algae cells that aggregate.  We have measured these products and found the vast fraction of particles are much larger than 10 microns, a majority larger than 50 microns, even after mixing in a blender. Feeding this food to rotifers means that very few of these particles are actually ingestible by rotifers, so it ends up polluting the water.

Flow through rotifer culture systems with a complete turn-over every two hours is, in our experience, sufficient to maintain excellent water quality. Feeding Amplifeed Replete four times a day takes only a few minutes, keeps the rotifers well fed, and does not “clog” the recommended 50 µM screens.

Closed Batch Systems: Rotifer mass cultures grown in open tanks are susceptible to invasion by competitors like ciliates. Our rotifer mass cultures are grown in closed 1000 liter bags with filtered water from an RO system and mixed with air filtered through a HEPA filter. We inoculate a batch culture with live Tetraselmis and algae nutrients and, when we see that the bag is turning quite green, we add rotifers or rotifer cysts (about one week at 25°C). The size of the rotifer inoculant is a function of how quickly one wants to reach a harvestable density. For example, a thousand liters is a million ml, so we harvest when rotifers reach about 400 per ml, so each bag provides us with 400 million rotifers. One can harvest a bag over several days to match one’s rotifer needs.

The nice thing about this system is that when one adds rotifers, there is a transition time where the metabolites produced by the rotifers are absorbed and utilized by the algae, maintaining good water quality in the culture. As the rotifers increase and consume most of the algae, the green fades and we begin adding 0.25 grams of Amplifeed Replete per million rotifers. Because this is a batch culture without addition of clean water, water quality eventually degrades and we have to harvest fairly rapidly.

Instructions for Use:


For rotifer culture, Amplifeed Replete may be used as a stand-alone feed or in conjunction with live algae. When live algae is used, it is possible to use less Amplifeed Replete, depending upon how much live algae is offered. It is usually easier to start rotifers from very low density (0.01 – 0.1 female/ml) on live algae. Amplifeed Replete is most effective once rotifers reach 1/ml and higher. For use as a sole feed, it is recommended to start with between 0.25-0.5g Amplifeed Replete per million rotifers per day. Feed rate or dosage will also vary based on rotifer species/strain, culture conditions, harvest rate, tank configuration, batch vs flow-through culture, and flow rate. Best results are obtained when Amplifeed Replete feeding rate is optimized for the specific culture systems employed by a hatchery.


To prepare feed, add appropriate amount of Amplifeed Replete to 500mL of fresh water (up to 50 grams per 500mL) use a kitchen blender to homogenize the mixture for 2-3 minutes before adding to the culture. This will assure that the feed remains in the water column for a long time and is therefore available to the rotifers.


For best results, the calculated daily Amplifeed Replete amount should be divided into 2 to 4 feedings per day. One should place water in the blender, start mixing, add the Amplifeed Replete and continue to blend for a 2-3 minutes. The blended mixture can then be added to the culture vessel.

A 50 µM mesh filter is used in the culture tank to retain the rotifers. An initial target turn over would be 600 liters an hour for a 1200 liter tank. Four, equally spaced feedings of 50 grams would be blended and added to the rotifer culture. Harvesting would allow the system to recover daily to 800 rotifers per ml from 500 rotifers a ml. Example of flow-through system harvesting 360 million rotifers a day:

Vessel Liter


Rotifers per ml


Harvest to

feed per million g














While this seems like a low density system, based on 20 years of experience at SA we have found that at densities much higher than 1000 per ml, the rotifers become stressed. We believe that culturing rotifer at high densities induces their stress hormones. While these hormones are part of the natural stress response of rotifers, we observe that they can be very harmful to fish larvae, which share many of the same stress hormones that are present in rotifers. If rotifer cultures are kept below a density of about 1000 per ml, induction of excessive stress hormones can be avoided. If a hatchery needs about 1 billion rotifers a day, three of these systems will very reliably produce healthy, nutritious rotifers day in and day out. Because of their modularity, these systems can be scaled to meet the rotifer needs of most hatcheries.

There is a wide-spread bias in aquaculture to operate rotifer production systems at very high densities, as high as 10,000 rotifers per ml. We believe that the costs in terms of reliability and quality have been grossly under estimated. The savings in capital, utilities, and labor of operating rotifer production systems at moderate densities more than compensate because of the higher reliability of these systems.

Amplifeed Replete’s advantages:

  • Cost effective.
  • Manufactured as a complete diet, algal content, fats, proteins, astaxanthin, folate, selenium etc.
  • Amplifeed Replete fed rotifers provide the best nutritional profile for larval fish to grow and mature rapidly
  • Manufactured to less than 10 microns so to allow near 100% consumption by rotifers.
  • Can support a flow through system using a 50 micron filter without “Clogging”.
  • Produces superior rotifers, seen in their color, body mass, and egg count.
  • Can be stored for a long time, best in a cooler or freezer in which case the shelf life can be years.
  • Takes most all the labor out of rotifer production, efficient, fast, limited resource demands, fewer operator errors.
  • High Reliability!
  • Proven, come visit SA!