Shellfish Diet 1800®

Shellfish Diet 1800® is a unique mix of six marine microalgae - Isochrysis, Pavlova, Tetraselmis, Chaetoceros calcitrans, Thalassiosira weissflogii and Thalassiosira pseudonana (New!) - species that have all demonstrated success with a variety of shellfish including oysters, clams, mussels, and scallops.

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This mixed diet provides excellent nutrition for bivalve species, from first feediing larvae all the way up through broodstock, increasing both growth rates and survival. Shellfish Diet 1800 is also an excellent feed for ascidians (tunicates), sea cucumber larvae, soft corals, Artemia, and some copepods.

The dry weight of Shellfish Diet is always 8%.  The cell count varies depending on the time of the year but is roughly 2 billion cells per ml (see Dry Weight vs Cell Count).

Note: Shellfish Diet is still available in its original formula upon request. Please contact us for more information.

Uses of Microalgae Concentrates for Rearing Oyster Larvae, Crassostrea virginica
F. Scott Rikard and William C. Walton, 2012

Auburn University Shellfish Laboratory tested three microalgae feeding protocols...

Applications: Shellfish Hatcheries

Related Products: ISO 1800 PAV 1800 TET 3600 TP 1800


Photomicrograph of Shellfish Diet

Oyster Larvae grown with SD

Shellfish Diet 1800 offers:

  • More DHA providing a healthy balance omega fatty acids, lipids and protein.
  • Diatoms for first feeding larvae (small sized Thalassiosira pseudonana)
  • a concentrated, clean, liquid form
  • a long shelf life of 18 – 24 weeks (refrigerated at 2-4 °C)

Shellfish Diet 1800 has been used successfully for:

  • Peak-load Supplement – Expand production while reducing live algae demand by feeding larvae Shellfish Diet 1800
  • Back-up Feed Supply – Shellfish Diet 1800 can be used as a partial or complete live algae replacement in the event of an algal system crash
  • Remote Set – Shellfish Diet 1800 is routinely used for remote setting of larvae, increasing the range of sites available for planting
  • Complete Algae Replacement – It works!It works! Some commercial hatcheries and numerous labs now do not grow their own microalgae, because they have found it more reliable and economical to feed exclusively Shellfish Diet 1800.

Applications

  • Effective at all life stages – larvae, setting, spat, fattening and maturation
  • Effective when used with open tanks, silos, bottle upwellers, header tanks (with circulation), cultch tanks and depuration tanks
  • Works best when there is moderate circulation to keep the algae suspended
  • Freshwater applications - Shellfish Diet is an effective feed for freshwater as well as marine organisms. Shellfish Diet and other Instant Algae products are widely used in freshwater mussel research.
  • Other uses of Shellfish Diet - Shellfish Diet is an effective feed for a wide range of filter feeders including bivalves, crustaceans, corals, and sea cucumber larvae

Feeding with Shellfish Diet

  • When feeding into open tanks or header tanks pre-dilute the algae 10:1 with seawater
    • We suggest pouring the slurry through a 20 to 50 micron mesh bag to ensure algae are dispersed.
  • When water is circulated with a centrifugal pump, such as with an upweller or downweller, Shellfish Diet can be added in front of the pump intake and the pump will disperse the algae cells
  • Do not use a blender to mix the algae!

Automated feeding for convenience and regulation of food density

Dispensing feed at frequent intervals makes it easier to maintain a steady food concentration in the culture tank, avoiding both overfeeding and underfeeding. A peristaltic pump, controlled by a timer, may be used to automatically dispense Shellfish Diet into the culture tank Shellfish Diet should be pumped from a reservoir housed in a refrigerator or ice-water bath. Experience has shown that the residence time of the feed in the tubing that delivers the feed to the culture tank is so short that this brief exposure to higher temperatures has no adverse effects on the quality of the feed.

A wealth of information on bivalve culture is available in the FAO's manual "Hatchery culture of bivalves", available as free download (be sure to download using the "ZIP" option, otherwise you will not get the complete manual). The following feeding rates are based on the FAO recommendations.

The following feeding rates are based on the FAO recommendations...

Feeding Rates

Feeding Larvae

Larviculture may run up to 20 days, but maximum feed is 20 mL/day/million larvae because there is no growth beyond 300 µm. Setting can be delayed if larvae are fully developed but do not set because they don’t detect suitable setting conditions.

Daily Feed Rates per million larvae, for Crassostrea virginica (from FAO protocol)

Day Mean Shell Length Billion cells of Isochrysis per million larvae Liters of Live Isochrysis at four million cells per ml ml of Shellfish Diet 1800 or Isochrysis 1800
2 75 1.7 0.4 0.4
3 95 2.2 0.6 0.6
4 100 2.8 0.7 0.7
5 115 8.5 2.1 2.2
6 130 14.5 3.6 3.8
7 145 20.5 5.1 5.4
8 160 26.2 6.6 6.9
9 190 37.9 9.5 9.9
10 220 49.7 12.4 13.0
11 240 57.5 14.4 15.1
12 260 65.3 16.3 17.1
13 270 69.2 17.3 18.2
14 280 73.1 18.3 19.2

Feeding Spat

Feed By Live Weight:

  • 0.7ml Shellfish Diet per gram live weight of spat per day
  • Works for all sizes of spat

– OR –

Feed by Seed Count:

(Feeding 1 million Oyster Spat; based on FAO manual, p. 137, Table 14)

Length (mm)Shellfish Diet feed per day
0.37 ml
0.550 ml
1.0214 ml
2.01.6 Liters
3.04.9 Liters

Feeding Broodstock (Conditioning) and Fattening Shellfish for Market

The required food ration for conditioning is based on the meat weight of the adults. It is usually between 2 and 4% of the mean dry meat in dry weight of algae fed per day. This is approximately equivalent to 0.03 – 0.06ml Shellfish Diet per gram of wet meat weight.

Typical Broodstock feed rates:

0.03 ‐ 0.06 ml Shellfish Diet per gram wet meat weight per day

– OR –

0.3 – 1.2 ml Shellfish Diet per adult animal per day

Batch Feeding - Dispensing Shellfish Diet

Shellfish Diet can be poured directly into the culture tank with stirring, but pre‐dilution is preferred.

Because Shellfish Diet is so highly concentrated, sometimes cells may form clumps when the feed is added directly to seawater, due to interaction of extracellular polysaccharides with polyvalent ions such as calcium (cf. gelling of alginate). An initial dilution (e.g., 1:10) with fresh water (free of Ca++ or Fe+++, which can also cause gelling), or even better a NaCl solution (typically 30 g/L; concentration is not critical), ensures that the cell‐to‐cell separation is great enough that cells cannot stick together when they are mixed into seawater. It also helps to pour the diluted feed through a 20 µm mesh filter—there is negligible retention on the mesh, and it ensures that dispersion is complete. Stir to mix feed; DO NOT MIX IN A BLENDER.

Automated feeding for convenience and regulation of food density

A peristaltic pump, controlled by a timer, may be used to automatically dispense Shellfish Diet into the culture tank. Dispensing feed at frequent intervals makes it possible to maintain a steady food concentration in the culture tank, avoiding both overfeeding and underfeeding. Shellfish Diet should be pumped from a reservoir housed in a refrigerator or ice‐water bath. Experience has shown that the residence time of the feed in the tubing that delivers the feed to the culture tank is so short that this brief exposure to higher temperatures has no adverse effects on the quality of the feed.

Dilution of the feed is particularly advantageous when it is dispensed by pump:

  • The increased volume reduces feed viscosity, so pumping is easier.
  • The increased volume requires faster pumping rates, which helps prevent the feed from settling in the lines.
  • Higher pumping rates are easier to measure and regulate (more difficult to precisely pump very small volumes).

The only disadvantages to dilution are the need for a larger feed reservoir, and the need to continuously stir the feed, because the reduced feed viscosity cannot maintain the algal cells in suspension. Some users stir the diluted feed with aeration or magnetic stirrers, but we found that a mini submersible pump (such as used in small aquariums or decorative garden fountains) is very cheap, reliable and effective. Their power consumption is typically 3 watts, so they contribute insignificant heat.

Freshwater applications

Shellfish Diet is an effective feed for freshwater as well as marine organisms. Shellfish Diet and other Instant Algae products are widely used in freshwater mussel research. Because the algal cells in these products are not living their cell membranes are not osmotic barriers, so the cells are not subject to swelling in fresh water.

Other uses of Shellfish Diet

Shellfish Diet is an effective feed for a wide range of filter feeders including bivalves, crustaceans, corals, and sea cucumber larvae.

Feed rates for bivalves

(see also here: Feeding Shellfish with Instant Algae)

One of the greatest advantages of feeding Shellfish Diet in place of phytoplankton cultures is that this feed provides a known concentration (dry weight) of food, whereas phytoplankton cultures normally must be monitored and frequently quantified (usually by cell counts) so they can be fed out at controlled rates. The simplest technique for feeding shellfish is by monitoring water color; add a dose of Shellfish Diet to the culture tank and watch how long it takes for the animals to clear it. If they clear it in less than 60 minutes, feed more, etc.. To obtain good growth, juvenile and adult shellfish should be fed at least is 1‐2 times each day, while for maintenance feeding can be as seldom as once per week.

Dry Weight vs. Cell Count

We specify the concentration of our Instant Algae products by biomass dry weight (Shellfish Diet is 80 g/L dry weight), not by cell count. There is such a large difference in cell volume (and biomass) for a small difference in cell diameter (volume is a cube function of diameter) that cell number is not a reliable measure of food value.

Product Description

DescriptionConcentrated Blend of Microalgae
Appearance Brown-Green Viscous Liquid
Algal size 4 - 20 microns
Microalgal Biomass > 8%

Composition of Biomass (dry wt)

Protein 52.0%
Lipid 16.1%
Carbohydrate 22.0%
Ash 9.9%

Microbial Specification

Coliform bacteria 2 <0.3 mpn/mL
Salmonella3 Negative
Known pathogenic
marine bacteria
Negative