Nutritional Quality
The nutritional quality of copepods is generally accepted to be very good for marine fish larvae, and believed to be of a higher quality than the commonly used live food Artemia. In general copepods have a high protein content (44-52%) and a good amino acid profile, with the exception of methionine and histidine (Table 5.4.).
The fatty acid composition of copepods varies considerably, since it reflects the fatty acid composition of the diet used during the culture. For example, the (n-3)HUFA content of individual adult Tisbe fed on Dunaliella (low (n-3)HUFA content) or Rhodomonas algae (high (n-3)HUFA content) is 39 ng, and 63 ng respectively, and corresponds to 0.8% and 1.3% of the dry weight. Within nauplii, the levels are relatively higher; (i.e. around 3.9% and 3.4%, respectively). Specific levels of EPA and DHA are respectively 6% and 17% in adults fed Dunaliella, and 18% and 32% in adults fed Rhodomonas. In nauplii the levels of EPA, DHA and (n-3)HUFA are high, (i.e. around 3.5%, 9.0% and 15%, respectively). The fatty acid profiles of Tigriopus japonicus cultured on baker’s yeast or Omega-yeast are shown in Table 5.5. and their respective nutritional value for flatfish larvae is shown in Table 5.6.
Differences in the biochemical composition, and in particular the HUFA content, are not the only advantages of copepods over Artemia when offered as food to marine fish larval. For example, copepods (copepodites and adults) are believed to contain higher levels of digestive enzymes which may play an important role during larval nutrition.
As mentioned previously, the early stages of many marine fish larvae do not have a well-developed digestive system and may benefit from the exogenous supply of enzymes from live food organisms. Evidence that copepods may be preferable to Artemia in this respect comes from Pederson (1984) who examined digestion in first-feeding herring larvae, and found that copepods passed more quickly through the gut and were better digested than Artemia.
We have had higher survival percentages and better coloration of seahorse fry, Clownfish larvae, and gobies when we started incorporating live copepods like “Reef Soup copepod mix” into our fish breeding programs.
Culturing and Feeding
In general, it may be stated that harpacticoid copepods are less sensitive and more tolerant to extreme changes in environmental conditions (i.e.salinity: 15-70 g.l-1; temperature: 17-30°C) than calanoids and thus are easier to rear under intensive conditions. Moreover, harpacticoids have a higher productivity than calanoids and can be fed on a wide variety of food items, such as microalgae, bacteria, detritus and even artificial diets. However, as mentioned previously, care should be taken in this respect as the lipid and (n-3) HUFA composition of the copepods is largely dependent on that of the diet fed.
How does routine additions and maintaining populations of copepods relate to your home reef tank?
All the same benefits that we get in aquaculture by using live zooplankton like copepods apply to keeping a healthy reef aquarium.
To obtain maximum results with your copepod culture and to maintain the highest possible densities in your Reef Aquarium, it is important to use a well proven copepod food like “Phytopreme Live” 6 types of concentrated live saltwater algae.
See the article called "Whole Life Cycle Aquarium" about the concept of setting up, incorporating and maintaining a reef tank with live zooplankton as an integral part of the system.