Feeding Shellfish with Instant Algae®
The most common technique for feeding shellfish is by monitoring water color. Simply add a dose of Instant Algae Shellfish Diet to you tank and watch how long it takes for the animals to clear it. If they clear it in less than 60 minutes, add more. The recommended schedule for juvenile and adult shellfish is 1-2 times each day, but can be as little as once per week.
Shellfish Diet feed per day (ml) = grams of broodstock meat (WET weight) x 0.036
Shellfish Diet feed per day (ml) = grams of broodstock meat (DRY weight) x 0.335
"a 3% ration for an adult of 0.75 g dry meat weight amounts to 0.0225 g dry weight of algae per day."
The hatchery culture of bivalves: a practical manual
Finishing the calculations...
The dry weight of Shellfish Diet is 8%. If the mussel meat dry weight is 0.75g per animal, for an oyster this would be about an 8g meat (wet). If you meat density or meat size is different, we will need to make adjustments.
Your feed rate should be 0.0225g/animal per day (from above) >> 0.281ml Shellfish Diet 1800 per animal per day.
300 mussels at 0.281ml/day = 84mls per day
84mls/day X 42 days = 3.5 liters of Shellfish Diet 1800
This amount needs to adjust upward (slightly) to account for algae loss in flow through systems (see the next section)
The most scientific information we have for determining feed amounts is from a study done in 1999 on post-set Crassostrea virginica oysters. The study measured feed rates for two objectives: optimal food conversion and optimal growth rate. The determination was that optimal food conversion occurred at 2% daily dry weight and optimal growth rate occurred at 5%.
For example, if you had 100 grams of oyster spat and wanted optimal growth rate you would feed them 5 grams of dry weight algae each day. If you were feeding them Instant Algae Shellfish Diet which has a dry weight of 8% you would need to use 55 grams of algae concentrate each day (5 grams / 8%). If you wanted optimal feeding conversion you would use 22 grams of Shellfish Diet (2 grams / 8%).
You can also use this formula for broodstock conditioning but you must first subtract the shell weight, leaving only the meat weight. For example, if you have 1000 grams of broodstock and 60% of the weight is shell, calculate the feed for 400 grams of meat weight. You can also reduce the intake to 1% of daily dry weight.
For information about using Instant Algae please click here. For best results use continuous feeding or in batch several times each day. Since bivalve shellfish are filter feeders good aeration and circulation will improve feeding rates and keep the algae well suspended in the water column.