Rotifers and the “Fish Egg standard”
It is often said that rotifers are simply nutrition delivery devices that mirror the nutritional profile of what the rotifers themselves are fed. In many respects this is true. However, this view underestimates both nutrition and rotifers.
The nutritional needs of first-feeding and early-stage marine fish larvae are very specific and critical. While some aspects of larval nutrition are well understood, many others remain obscure.
Moreover, rotifers are not simply passive carriers. They break down and reassemble lipids, proteins and other nutrients. This means they are biochemically active and contain active enzymes, co-enzymes, partially digested lipids and proteins, and a host of more complex nutritional factors. Ultimately, hatcheries use rotifers because rotifers work, and because artificial diets have not yet been formulated that can replace rotifers.
It is important to evaluate rotifer feeds and enrichments by the final nutritional profile of the digestible portion of the rotifers fed to fish larvae.
This profile is clearly different from the nutritional profile of the feed and enrichments. However, the nutritional profile of rotifer feeds is critical for the health and value of cultured rotifers and how the rotifers segment the nutrition they take up. A classic example is HUFA lipids. HUFAs that are consumed over time tend to be incorporated as phospholipid tissue while HUFAs that are taken up rapidly are more likely to be segmented to triglyceride energy stores and less digestible egg tissue.
- The Fish Egg Standard
- Enzymes and probiotics
- Fatty acids
- Lipid class
- Minerals and more