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.

Batch Feeding - Dispensing Shellfish Diet

Excellent results are achieved feeding Shellfish Diet with two or more batch feedings per day. Shellfish Diet can be poured directly into a culture tank with adequate circulation, but pre-dilution is strongly recommended.

Shellfish Diet is highly concentrated. Without pre-dilution, cells may form small clumps when the feed is added directly to seawater. An initial dilution (e.g., 1:10) with fresh water (free of Ca++ or Fe+++), or even better a NaCl solution, ensures that cells do not stick together when they are mixed into seawater. We also recommend pouring the diluted feed through a 20 μm sock filter—there is negligible retention on the sock, 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.

The preferred protocol is: (1) add the desired amount of pre-diluted feed to a 5 gallon bucket. (2) Fill the bucket to 16 liters with NaCl water. (3) Add Reed Mariculture's buffer mix at a rate of 100g per liter of feed. (4) Keep the mixture suspended with a low-shear micro-submersible pump, aeration, or magnetic stirrer. Low-shear micro-submersible pumps are available from Reed Mariculture. (5) Pump to your culture tank with a 15 liter per day peristaltic pump, or a higher-flow pump controlled by an interval cycle timer. If you have any questions, please contact us.

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. Information about bivalve feed rates can be found here: Feeding Shellfish with Instant Algae.

One of the great advantages of feeding Shellfish Diet is that the feed provides a known concentration (dry weight) of food, whereas phytoplankton cultures normally must be monitored and frequently quantified. The simplest technique for feeding shellfish is monitoring water color; add a dose of Shellfish Diet to the culture tank and watch how long it takes for the animals to clear the water. If they clear it in less than 60 minutes, feed more. 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

A full explanation can be found here.

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.

Feeding Larvae

See the Technical Info Tab

Feeding Spat

At 1 mm shell length, individual oyster spat live weight (shell and body) is ~0.3 mg. Clam and scallop spat are about 30% lighter than oyster spat for a given shell length, within the size range grown in hatcheries.

Feed rate is calculated from the equation: Feed [F] = (Live weight [S] x Feed rate [R]) ÷ 80

F = the volume of Instant Algae Shellfish Diet per day (L)
S = the live weight of spat (g) at the beginning of each week
R = ration as dry weight of algae (g) per g live weight of spat per day
A typical value for R = 0.057 g dry weight of algae per g live weight of spat per day
To feed 1,000,000 oyster spat, F = (300 x 0.057) = 17.1 g dry wt of algae = 0.214 L/day of Shellfish Diet

Broodstock conditioning

The required food ration for conditioning is based on the meat dry weight of the adults. It is usually between 2 and 4% of the mean weight of the adults at the start of conditioning, in dry weight of algae fed per day. Typical Broodstock feed rates: 3.6 mL Shellfish Diet per 100 g of broodstock meat (WET weight)

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

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