PRELIMINARY ESTIMATION OF TROPICAL ORNAMENTAL FISH METABOLITE PRODUCTION-RATES

The rational design of closed aquaculture systems requires data on metabolite production rates. The metabolite of primary concern is often ammonia. Ammonia formation rates for a number of tropical ornamental fish types and sizes were determined. Cyprinus carpio, Barbus conchonius, Pseudotropheus auratus and Carassius auratus auratus were used as representative egg-layers while Xiphophorus variatus and Xiphophorus helleri represented the live-bearers. Specific metabolite production rates, R', were determined not only in terms of mass of fish but also the amount of feed. For instance, R' (Amm-N) for 1.33 g unit size Barbus conchonius was determined to be 155.9 mg Amm-N kg-fish-1% feed-1 day-1. In an attempt to produce a general model for all the ornamental fish investigated, all values of R' obtained were correlated with fish sizes to produce an equation R' (Amm-N) = 1.57-[30 x log (UW)] where UW = unit fish size.