The Israeli Journal of Aquaculture - Bamidgeh 55(4), 2003
The 7th Annual Dan Popper Symposium
MODELING OF ENERGY AND NUTRIENT BUDGETS IN
INTENSIVE AQUACULTURE SYSTEMS
Ingrid Lupatsch* and G. Wm. Kissil
Israel Oceanographic and Limnological Research Ltd., National Center for Mariculture,
P.O. Box 1212, Eilat 88112, Israel
The quantification of feed, fish growth and metabolism represent the primary processes for
which recirculating aquaculture (RAS) fish culture systems are designed and managed. As fish
feed is considered the only source of nutrients, total food input equals retention (fish growth) plus
feces (solid waste) and excretion (dissolved waste).
This paper describes a model that can be used to quantify the necessary energy and nutrient
intake of gilthead sea bream for optimal growth and predict the retention efficiency and outputs
of solid and dissolved nutrients. The total energy and nutrient requirements in growing fish
are the sum of those needed for maintenance and growth. The requirement for maintenance is
mainly a function of the size of the fish and water temperature, and is proportional to the metabolic
body weight (kg) 0.80. The requirement for growth, on the other hand, depends mainly on the
weight gain and the composition of that gain.
This model can be used to formulate practical feeds for gilthead sea bream and determine
optimal feeding tables that supply the necessary daily amount of energy and protein. Once the
digestibility of the feed is determined, solid waste production can be estimated. Total dissolved
ammonia nitrogen can be calculated as the difference between nitrogen intake and retention (as
growth) plus fecal matter. By incorporating the oxygen equivalent per unit of energy required by
the fish, O2 demand and subsequent CO2 excretion can be determined for increasing fish weights and different production levels.
The equations can easily be incorporated into a computer program and used to predict fish
production, feed demand, FCR, oxygen demand and waste production. The output of the model
is the basis for designing culture system volumes, water flow rates, solid filters, biofilters, oxygenation
and CO2 stripping devices in RAS.