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Instant Algae Rotifer Recipe

Instant Algae^® is an excellent feed for producing large quantities of highly nutritious rotifers. Microalgae is the natural food for rotifers and provides the highest growth and fertility rates of any rotifer feed. By using a combination of Instant Algae^® products you can create the optimal EPA / DHA / ARA profile for your target species.

Note: The following is general information. As with any type of live culture, care should be taken to adapt this to your own situation

Contents

Formula for rapid rotifer growth and fertility	100% Nannochloropsis
Formula for DHA Enrichment	Use either Isochrysis or Pavlova for 4 hours
Feeding rate	1 bag of Instant Algae® Nannochloropsis 3600 will harvest 500 million "L" type rotifers each day
How often to feed	Continuous feeding is better than batch feeding
Improving culture performance	Avoiding factors that "shock" the rotifer culture
Tips on starting a rotifer culture
Low Density rotifer culture
High Density rotifer systems (intensive commercial scale operation)

Feeding Rotifers

Microalgae vs. Other Feeds

Rotifers themselves have little nutritional value - they act as "nutrient carriers" for transporting the high-value essential fatty acids (EPA and DHA) and other nutrients from the microalgae to the target species. Although you can feed rotifers a variety of items such as yeast, the rotifers will only be as nutritious as the feed they have ingested. An empty or poorly enriched (fed) rotifer will provide little value to your larvae.

Marine microalgae is widely recognized as the best feed for growing and enriching rotifers. Microalgae is what rotifers naturally feed on in the wild, and provides the complete chemical composition that larval fish need for proper neural development. It is also the easiest feed to work with. Yeast and emulsion products rapidly foul a rotifer cultures, creating high levels of bacteria and ammonia, and causing the rotifers to stick together. Microalgae such Nannochloropsis have a tough shell wall that resists bacterial breakdown for up to 48 hours so there is no fouling, bacteria, or stickiness.

Formula for growth and fertility

The best feed for growing rotifers is 100% Nannochloropsis. Nannochloropsis is a small green algae (2 microns) that has a very high lipid, protein, and calorie profile. This algae will give your rotifers a very high nutritional and EPA profile. We recommend 1.5 ml's of Nannochloropsis for each 1 million rotifers each day.

Formula for DHA Enrichment

The best algae for DHA enrichment is either Isochrysis or Pavlova which contains 10% DHA as a percentage of lipids. DHA enrichment is done during the last 4-8 hours before feeding the rotifers to your animals. We recommend 3 ml's of Isochrysis or Pavlova for every 1 million rotifers each day.

How much to feed

The following information is based on Reed Mariculture's observations from growing "L" type rotifers at our facility, using a simple continuous culture system.

Rotifers are voracious animals - a single (L) strain rotifer will consume about 115,000 cells of Nannochloropsis each day. Instant Algae^® Nannochloropsis 3600 contains 68 billion cells per ml (68 trillion per bag) and will feed about 600 million (L) rotifers or 1 billion (S) or (SS) rotifers each day. In low density cultures (< 1,000 / ml) you will find that the rotifers need about 1/3 more algae than in high density cultures.

Nannochloropsis is the best single algae we have found for growing rotifers. We recommend 1.5 ml's of Nannochloropsis for each 1 million "L" type rotifers each day. If you are using S or SS type rotifers use 1.5 ml for each 2-3 million rotifers.

For DHA enrichment we recommend 3 ml's of Isochrysis or Pavlova for every 1 million "L" type rotifers each day. If you have S or SS type rotifers feed 3 ml's for each 2-3 million rotifers.

How often to feed

The key to successfully maintaining a rotifer culture is keeping the right amount of algae in the water at all times. If you add too much algae it will not be eaten and create detritus and bacteria. If you add too little algae your animals will be hungry and become "shocked".

Unlike larger animals that can store fat, rotifers need to feed continuously. Due to their high metabolism, about 2-4 hours after a batch feeding they will be empty and starting to starve which "shocks" their system and disrupts their reproduction. Rotifers need a consistent supply of "free" algae in the water at all times, allowing them to graze continuously. When using an algae concentrate setting up a continuous feeding system is easy and inexpensive.

Ammonia Control

Ammonia toxicity is one of the biggest challenges with rotifer production. Rotifers have a very high metabolism and produce a lot of waste, which converts to ammonia and can quickly reach toxic levels. We use (and sell) an ammonia neutralizer called ClorAm-X with our rotifers, both in the grow-out tanks and for shipping the animals.  We use about 150 grams of ClorAm-X with each 1 liter bag of Nannochloropsis, or 600 million rotifers.

Reed Mariculture's Continuous Rotifer System

• This page has been moved to rotifer.reed-mariculture.com/bioreactor.asp.

Setting up a continuous feed system

• Once or twice each day fill a jar or bucket with water from your tank and add the measured amount of microalgae formula (see above for amount to use).
• Place the jar above the tank and use a plastic hose to establish a siphon into the tank. Regulate the flow by pinching the hose with a clip until it slowly drips the algae into the tank at a steady rate.  If possible, put an air stone in the bucket to maintain aeration.
• OR purchase a small metering pump ($150-200) to dose the tank every minute.
• If you are in a warm climate you will need to keep the jar of algae concentrate cool. Putting a cool object in the jar with the algae can maintain proper temperatures. Some hatcheries use gel ice bags and rotate them between the freezer and the jar of algae concentrate every 6-12 hours.

Microalgae Ice Cubes

Instant Algae^® Nannochloropsis 3600 can be frozen into small ice cubes which has the dual benefit of creating a pre-measured quantity of algae, and extends the shelf life of the algae. To make microalgae ice cubes simply pour the algae into cheap plastic ice cube trays (available at your local store) and store in the freezer overnight. When frozen, break the cubes out of the trays and store them in a plastic bag in your freezer. By measuring one of the cubes you will know the weight of all the cubes, simplifying your future feeding protocol. As needed, take 1 or more cubes from the freezer and dissolve them in a jar with water from your tank (see "continuous feed system" above). If you have extra algae remaining put it in your refrigerator where it will last for several days.

Improving Culture Performance

There are several variables that can "shock" your rotifers, decreasing their growth and fertility rates. The most common are a change in temperature, pH, or salinity in the rotifer culture. Typically these "shocks" come from feeding large amounts of live algae but can also be caused by other factors.

Microalgae is a plant and requires large amounts of plant fertilizers such as nitrates, phosphates, and iron. These are good for plants but somewhat toxic for animals. Microalgae cultures can have higher pH levels than rotifer cultures due to photosynthesis.

For best growth and nutritional value algae are typically grown at 16-24 C while rotifers are grown at 26-30 C. When the algae culture that is full of fertilizers, has a different pH, and a lower temperature is introduced into your rotifer culture, it "shocks" to the culture. This can cause weak animals to die, healthy animals to stop feeding for several hours, and females to stop egg production.

The rotifer culture should be maintained at a pH around 8. At a pH lower than 7.2 or higher than 9 the culture will have significant mortality.

Algae concentrates work quite differently from live algae in rotifer cultures:

• During the harvesting process most of the fertilizers are removed from the algae along with the water.
• When the algae concentrate is added to the rotifer culture the pH in the tank is virtually unaffected since the relative biomass of the algae is so small.
• Temperature is not a problem because the slow drip of concentrated algae does not affect the tank temperature.

For these reasons you will find that almost all commercial high density ( > 1,000/ml) rotifer bioreactors use algae concentrates rather than live algae cultures.

Tips on starting a rotifer culture

• Feed rates should be based on the actual density of rotifers in the system and care should be taken not to overfeed.
• If feeding continuously the drip rate should be monitored to avoid excess algae accumulation.
• If batch feeding, the culture tank should clear of algae before the next feeding to avoid excess algae accumulation.
• Any algae that is not consumed within 48 hours will degrade, increasing the level of ammonia and decrease the dissolved oxygen levels.
• Care should be taken to match the salinity of the rotifer tank to the salinity of the starter culture

Low Density Rotifer Culture (10-300 / ml)

Reef hobbyists, aquarium stores and small and large hatcheries use low density rotifer cultures to provide feed to larval fish. Instant Algae^® products can be used as a complete replacement for live algae.

Sterilized seawater should always be used to fill rotifer culture tanks. The water should be adjusted to match the pH and temperature of the starter culture. Optimal temperature is 20 - 30° C and pH is 8.0. Cultures should be started with a minimum of 10-20 rotifers per ml to minimize the possibility of a crash. Cultures can be maintained on 1-2 feedings per day; however continuous feeding or several small feedings per day are preferable. Rotifer counts should be taken daily to determine the health of the culture. Healthy cultures of rotifers contain egg bearing females and very few males. An increase in the number of male rotifers, easily identifiable by their smaller size, is an indicator of a stressed culture. In such a case the water quality should be tested and appropriate action should be taken.

In small aquariums (<30 gallons), it is best not to exceed 300 rotifers per ml. As the volume of the culture container increases the density of rotifers can also be increased. (see Table 1 for additional system guidelines). Experienced culturists have exceeded 700 rotifers per ml in batch culture systems. Semi-continuous cultures can be maintained by doing a 30-50% water change and rotifer harvest. The culture should rebound to have the same densities the next day, allowing for a daily harvest. Over time, the culture will need to be restarted to avoid waste build-up and bacterial blooms that can cause a culture crash. Semi-continuous cultures can be maintained for a week or more before restarting.

Low aeration is needed to keep adequate dissolved oxygen levels and to maintain rotifers and algae paste in suspension. The tank should look as though it is very lightly boiling. Over-aerating can result in excessive evaporation, foam production and rotifer loss. Lighting is not necessary for good rotifer growth. In the Instant Algae Rotifer System we actually "black-out" the tank to inhibit growth of algae and other organisms in the tank.

High Density Rotifer Culture (700-2000)

High density rotifer culture is necessary when large volumes of rotifers are needed each day. These systems can be run in batch type culture as well as continuous culture systems. These high density systems must have carefully controlled environments. A pH controlling system, feed dosing system and pure oxygen additions are necessary to maintain these high density cultures. Optimal pH in these systems is 8. This helps lower the toxicity of the total unionized ammonia. Continuous high density rotifer systems require the use of biological and mechanical filtration. With biological filtration pH is not as crucial and pH-dosing systems can be eliminated.

High density rotifer cultures vary in size from 40 to over 250 gallons. For beginners it is more reasonable to expect 500-700 per ml while more experience culturist can achieve > 2000 per ml. In high density rotifer systems the use of an algae concentrate such as Instant Algae^® is necessary to reach the desired densities because of the "shock" factors from feeding large amounts of live algae, as well as the high cost of producing the necessary amounts of live algae. The ultimate goal is to have as much feed as possible (without overfeeding) with optimal temperature, and oxygen levels. Enrichment can be accomplished through traditional methods of feeding Isochrysis in the last few hours before feeding them to your animals.

For information about the Instant Algae High Output Rotifer System click here.

Super High Density Rotifer Culture (2,000 - 15,000)

Densities over 15,000 per ml have been exceeded in sophisticated recirculating systems. Unfortunately there are no real guidelines for super high density rotifer culture. More information on this type of system is available from Amy Riedel @ Aquatic Eco-Systems Inc. (amyr@aquaticeco.com / 1-800-422-3939).