BENTHIC COPEPODS AS A REPLACEMENT FOR Artemia NAUPLII: ADVANTAGES FOR SMALL-SCALE AQUACULTURE PRODUCTION

Small-scale aquaculture is an important component of the ornamental aquarium trade. These fish culturists have fewer resources when compared to commercial-scale producers and must run their operations with far less labor than established companies. When considering labor expenses, some of the largest time consumers are live microalgae and Artemia cultures. Artemia nauplii grow rather quickly, requiring fish culturists to constantly hatch new batches. Artemia supply can vary in cost and availability, adding uncertainty to the costs of production.

Copepods are essential in the production of many ornamental marine species. Researchers have worked with several species (e.g., Parvocalinus crassirostris; Pseudodiaptomus pelagicus) - providing larval fish with copepod nauplii harvested from a stock culture daily. Production is typically done on a larger scale than that of a home breeder and requires a large labor demand including the general necessity of culturing live microalgae as feed for the copepods.

Recent refinements in microalgae concentrates have provided alternatives that eliminate the need for live phytoplankton cultures. These concentrates provide a cost advantage over live microalgae production (less time and labor), and are now a go-to for live rotifer cultures; however, many aquaculturists have had little luck sustaining copepod cultures on non-viable microalgae concentrates.

Some copepod species, including the benthic Tisbe biminiensis harpacticoids, prefer heterotrophic food sources as opposed to autotrophic microalgae diets. These scavenger copepods may provide not only a food source, but as detritivores may also assist in the break-down and cycling of nutrients in static larval nursery tanks (the common type of system for the hobbyist-level breeder). Additionally, these benthic copepod adults remain below the water column, which results in low predation by larger larval fish and thus enables the perpetuation of a broad range of nauplii sizes within the static nursery tank. This method may provide a low-cost alternative to the production and provision of live microalgae and Artemia.

To quantify the success rate of this technique, two treatments of newly-hatched clownfish larvae were provided with live rotifers followed by the transition to (1) copepods or (2) Artemia nauplii. We examined two species of clownfish, Amphiprion ocellaris and A. frenatus. In both treatments larval clownfish were fed an appropriate quantity of prey items and water was tinted green using microalgae concentrate. Detritus was not siphoned from either treatment (but mortalities were removed and recorded). Additionally, labor hours for each treatment were recorded including culture maintenance, feed preparation, and clean-up. Trials culminated at metamorphosis (i.e., when young fish are generally weaned onto a formulated diet).

This study identifies differences in cost, time, and success rate of the two rearing techniques to identify potential cost-saving advantages of using the benthic Tisbe biminiensis copepod in the culture of A. ocellaris and A. frenatus clownfish.