Feeding Trials

Phytoplankton Has Importance
Far Beyond Aquarium Use.

Phytoplankton is essential for the commercial production of clams, scallops, mussels, shrimp (larval stage) and also for raising and enriching the food for fish larvae. There are several companies producing products to supplement live phytoplankton for commercial use. These products are now being marketed for aquarium use even though home aquaria greatly differ from commercial systems.

Because of its importance in aquaculture, phytoplankton is looked at more closely than just about any other aquarium product. Feeding trials were conducted to test the shelf life and nutritional claims of several phytoplankton products. These trials were conducted by Dr. Robert Toonen at the University of California, Davis on invertebrate larvae that need phytoplankton not only to grow but to survive.

The following information is the result of these trials:
Test larvae: Anisdoris (dorid sea slug), Diaulula (dorid sea slug), Lacuna (snail) and Sabellaria (sand-castle worm).
Control: Live from active culture Nannochloropsis oculata (Nanno)
Placebo: Filtered seawater

Dried phytoplankton clumps together to an average particle size far too large for phytoplankton feeders. The longer this product was stored, the larger the average particle size. There is also ample evidence that drying adversely affects at least some of the nutrients in algae.

The rate of nutritional decline in preserved algae is determined by temperature. The colder this product is stored, the longer it retains nutrients. The reason that such deep freezing is required is that protein denaturation continue to occur at temperatures above -80C, although it is slowed considerably, and some enzymatic processes continue, even at these extremely cold temperatures. The shelf life of this product drops off quickly, unless it’s stored at temperatures far below those of a household freezer.

Extreme cold under laboratory conditions: -42C= -43.6F

Normal household freezer at coldest setting: -20C= -4F

This species was most likely affected by either the concentration or freezing process used, and has very little nutritional value unless it is alive and fresh. Some companies boast of T-iso as being a part of their frozen blend even though it has such little value.

Phytoplankton are very fast growing plants that exhaust available nutrients quickly. To be as nutritionally rich as possible, phytoplankton must be harvested before it becomes nitrogen starved. If kept refrigerated, live phytoplankton remains nutritious for nearly six months. If kept active in a state of nitrogen starvation, phytoplankton loses its nutritional value within a week, even though it stays alive. The best if used by date on DT's Live Marine Phytoplankton, is based on five months from harvest.