The Israeli Journal of Aquaculture - Bamidgeh 55(4), 2003
The 7th Annual Dan Popper Symposium


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.