The RATION Table

Trophic relationships define an ecosystem

Like other heterotrophic organisms, fish need food to survive and grow. Within ecosystems, trophic relationships and energy flows largely define the function of various species (see Box 21, and contributions in Christensen and Pauly 1993). There are two ways of presenting species-specific consumption:

  • at the individual level, i.e., as the consumption of a particular food type by a fish of a certain size, i.e., in the form of a daily ration (Rd); or

  • at the population level, i.e., as the consumption (Q) by an age-structured population of weight (B), i.e., in form of population-weighted consumption per unit biomass (Q/B).

Pauly (1986) and Palomares and Pauly (1989) discuss the relationship between these two measures and methods for their estimation. The RATION table described here and the Q/B table described further below over 400 records of Rd in over 60 species and over 160 records of Q/B in about 100 species, mostly derived from Palomares (1987), Palomares and Pauly (1989), Pauly (1989) and Palomares (1991).


The bulk of the entries in this table was taken from work performed by the first author, or with which she was closely associated. Names of food items were verified against the classification used in the Taxonomic Code of the National Oceanographic Data Center (NODC) (Hardy 1993).

We recall that the term ‘ration’ (Rd) pertains to an estimate of daily food consumption by fish of a specific size. This table presents ration estimates and related parameters. Its fields are as follows:

  • Ration (% BWD, i.e., weight of food injected in a day × 100/body weight);

  • Evacuation rate (the fraction of the stomach content which is passed through the hindgut per hour); and

  • K1 (= food conversion efficiency = growth in weight / weight of food ingested) over a given period.

Daily ration, evacuation rate and K1 vary with the weight of the studied fish (Fig. 39), with the type of food ingested, and the mean temperature (in ºC) of the water where the fish occurs. Both Weight of fish and Water temp. are numeric fields. The Salinity field pertains to the body of water where the fish was sampled or to the medium of experiment and includes the choices: seawater; brackish water; freshwater.

Food types are classified in multiple choice fields

Food type is described using two choice fields: Food I has six choices of functional groups: detritus; plants; zoobenthos; zooplankton; nekton; others. Food II provides more detailed groupings of food items following the hierarchy described in the FOOD ITEMS table and Box 24. Both of these fields include the choice ‘others’ for items not in the lists. The Food name text field is provided for more specific descriptions, e.g., the scientific or common name of the food item. Artificial food (all types of prepared feed such as pellets and fishmeal) is specified in the Food name field with a brief description of the preparation, e.g., moist or dry pellets.

Methods used to estimate Evacuation rate and Daily ration are given. Evacuation rate is generally estimated from either of two general approaches:

  1. laboratory studies involving sequential slaughtering or pumping out the stomach of a batch of fish fed at the same time (see Elliott and Persson 1978); or

  2. fitting of a theoretically-derived model to stomach contents of wild-caught fish, covering a daily cycle (see, e.g., Sainsbury 1986).

The software package developed at ICLARM to implement the model of Sainsbury (1986), MAXIMS (see Jarre et al. 1991), is now widely used for the second approach. It is thus included as a choice for the Method used field for evacuation rate estimation. The other choices included in this field are ‘laboratory experiments’ as in (1) above and ‘other’.

Fig. 39. Relative ration of Gadus morhua (black dots) compared with that of other fishes, whose large scatter is due to different food types, environmental temperature and other variables that will be standardized in future versions of this graph.

The methods available in the choice list for the estimation of Daily ration are: use of stomach contents data with the MAXIMS software; through the product of evacuation rate and mean stomach content (Elliott and Persson 1978); other methods based on gut contents analyses (e.g., Bajkov 1935; Gorelova 1984); indirect estimates, from Winberg’s metabolic model (Winberg 1956; Mann 1978); oxygen consumption studies (Wakeman et al. 1979); and feeding experiments and/or estimates of K1 (see Pauly 1986). The choice ‘other’ is provided for cases when the method used is not in the list. Here, the method must be specified in the Comments field.

We anticipate that the number of species and stocks covered by this table will increase in the future, as suitable datasets have been made available, notably at the annual Science Meetings of the International Council for the Exploration of the Sea.

How to get there

You get to the RATION table by clicking on the Biology button in the SPECIES window, the Trophic Ecology button in the BIOLOGY window, and the Ration button in the TROPHIC ECOLOGY window.

You get to the graph of ration vs. body weight by clicking the Graph button in the upper right corner of the LIST OF RATION STUDIES window.


On the Internet, you get to the RATION table by clicking on the respective link in the ‘More information’ section of the ‘Species Summary’ page. You can create a list of species with available Ration data by selecting the respective radio button in the ‘Information by Topic’ section of the ‘Search FishBase’ page.


Bajkov, A.D. 1935. How to estimate the daily food consumption of fish under natural conditions. Trans. Am. Fish. Soc. 65:288-289.

Christensen, V. and D. Pauly, Editors. 1993. Trophic models of aquatic ecosystems. ICLARM Conf. Proc. 26, 390 p.

Elliott, J.M. and L. Persson. 1978. The estimation of daily rates of food consumption for fish. J. Anim. Ecol. 47:977-993.

Gorelova, T.A. 1984. A quantitative assessment of consumption of zooplankton by epipelagic lantern fishes (Family Myctophidae) in the equatorial Pacific Ocean. J. Ichthyol. 23(3):106-113.

Hardy, J.D. 1993. NODC taxonomic code links biology and computerized data processing. Earth Systems Monitor 21(2):1-2.

Jarre, A., M.L. Palomares, M.L. Soriano, V.C. Sambilay, Jr. and D. Pauly. 1991. Some new analytical and comparative methods for estimating the food consumption of fish. ICES Mar. Sci. Symp. 193:99-108.

Mann, K.H. 1978. Estimating the food consumption of fish in nature, p. 250-273. In S.D. Gerking (ed.) Ecology of freshwater fish production. Blackwell Scientific Publications, Oxford.

Palomares, M.L.D. 1987. Comparative studies on the food consumption of marine fishes with emphasis on species occurring in the Philippines. Institute of Biology, College of Science, University of the Philippines, Diliman, Quezon City. 107 p. MS thesis.

Palomares, M.L.D. 1991. La consommation de nourriture chez les poissons: étude comparative, mise au point d’un modèle predictif et application à l’étude des réseaux trophiques. Ecole Nationale Supérieure, Institut National Polytechnique de Toulouse. 211 p. PhD thesis.

Palomares, M.L. and D. Pauly. 1989. A multiple regression model for predicting the food consumption of marine fish populations. Aust. J. Mar. Freshwat. Res. 40:259-273.

Pauly, D. 1986. A simple method for estimating the food consumption of fish populations from growth data and food conversion experiments. Fish. Bull. 84(4):827-839.

Pauly, D. 1989. Food consumption by tropical and temperate marine fishes: some generalizations. J. Fish Biol. 35 (Supplement A):11-20.

Sainsbury, K.J. 1986. Estimation of food consumption from field observations of fish feeding cycles. J. Fish Biol. 29:23-36.

Wakeman, J.M., C.R. Arnold, D.E. Wohlschlag and S.C. Rabalais. 1979. Oxygen consumption, energy expenditure and growth of the red snapper (Lutjanus campechanus). Trans. Am. Fish. Soc. 108:288-292.

Winberg, G.G. 1956. Rate of metabolism and food requirements of fishes. Fish. Res. Board Can. Trans. Ser. No. 194.

Maria Lourdes D. Palomares and Daniel Pauly