The PREDATORS table lists the reported predators of a particular fish species. This table includes a Locality field; Predator classification fields, Predator group and name; Prey stage and its contribution to the diet of the predator, in percent. The information compiled in this table may be of use to fishery and conservation workers, as predator-prey relationships may help explain the status of some fish stocks. The information is also used for the construction of TROPHIC PYRAMIDS (this vol.). In addition, this information can be used to test current hypotheses about the relative sizes of prey and predators (Box 29; see also Fig. 41).

Predator-prey relationships explain the status of some fish stocks

The records in the PREDATORS table (>3,000 records for >1,200 species) were extracted from over 380 references such as Hiatt and Strasburg (1960), Randall (1967), Scott and Crossman (1973), Mathews et al. (1977), Ebert et al. (1991), Uchida (1981), Collette and Nauen (1983), Meyer and Smale (1991), Hensley and Hensley (1995) and Tokranov and Maksimenkov (1995). The taxonomic classification of predator species other than fish was checked against the Taxonomic Code (Hardy 1993) and the Taxonomic Authority List of the Aquatic Sciences and Fisheries Information System (de Luca 1988).


The PREDATORS table consists of the following fields:

The Country/locality field refers to the site where the study was undertaken.

The choices in the Predator I and Predator II fields are given in Box 28.

The Predator Group is a free text field referring to the family or major group of the predator species.

The Predator Name is a free text field referring to the scientific or common name of the predator species.

The Predator Stage is a choice field referring to the stage of development of the predator species with the following options: larvae; recruits/juv.; juv./adults; adults.

Box 28. Hierarchy of predators.

To standardize the choices provided for the predator fields of the PREDATORS table of FishBase, a hierarchy like that for food items was created, roughly analogous to the Food I-III choices in the FOOD ITEMS table (see Box 24). These are:


Predator I

Predator II


jellyfish/ hydroids; sea anemones; corals


gastropods; squids/cuttlefish; octopus


copepods; mysids; isopods; amphipods; stomatopods; euphausiids; shrimps/prawns; lobsters; crabs; other crustaceans




sea stars


sharks/rays; bony fish; n.a./other finfish


salamanders/newts; toads/frogs; crocodiles; turtles; snakes


sea birds; shore birds


whales/dolphins; seals/sea lions




This hierarchy includes only animals commonly reported to consume fish including fish larvae. Groups that feed only occasionally on fish (as do, e.g., South American ostriches, see Darwin 1845) such as tunicates feeding e.g., on Vinciguerria must be entered in the ‘others’ category and specified in the Food Group field.


Darwin, C. 1845. Journal of researches into the natural history and geology of the countries visited during the voyage of H.M.S. Beagle. Murray, London.


Maria Lourdes D. Palomares, Pascualita Sa-a and Daniel Pauly


The % of stomach contents field refers to the percentage weight or volume by which the prey contributes to the stomach contents of a predator. If a precise percentage of volume is not available, an indicator of the ‘commonness’ of the prey item in the diet of the particular predator is provided in the field beside it.

Big fish eat small fish

For both Prey and Predator Stage, the juv./adults option is the default when no stage is specified in the references for either prey or predator species.

The Prey Stage is a choice field referring to the stage of development of the prey species with the following options: eggs; larvae; recruits/juv.; juv./adults; adults.

The Remarks field is used to describe or specify the prey item that was classified as ‘other’ in the Predator I and II fields or other pertinent information.

Box 29. Predator-prey ratios in fishes.

Relating the size of predatory fishes to the size of their fish prey was our first analysis confirming the ability of FishBase to test relatively complex hypotheses, using data not initially gathered for that purpose.

The hypotheses tested here were:

  • that the ratios of predator : prey sizes are similar among fishes of different species, and in the neighborhood of 4 : 1 when sizes are expressed as body lengths; and
  • that the residuals about the mean predator : prey sizes are log-normally distributed, as postulated by Ursin (1973).

The data used to test these hypotheses were extracted from the DIET table, i.e., all cases where the prey is a fish, its life stage was entered, its length is available in the SPECIES table and is of the same length type as the predator’s, and its calculated prey length (see below) is smaller than the predator’s, to exclude parasitic fish such as lampreys.

Very few food and feeding habit studies in the literature indicate the size of ingested organisms, and hence the DIET and PREDATORS tables do not include fields for these. In the absence of size data specific to each study, the size (=length) of predators and prey were estimated as follows:

  • for each species, read the maximum length (Lmax) and the common length (Lcom) in the SPECIES table;
  • for predators or prey for which the stage is ‘adult’, use Lcom as 64% of Lmax. [This was decided after verifying that in species for which both entries exist, Lcom is on the average 0.64 * Lmax];
  • for all species for which the life stage of the predator was ‘juveniles and adults’, use ½ of Lmax;
  • for all species for which the life stage is ‘juveniles’, use 1/3 of Lmax.

[Note that this treatment ignores cases where the prey are fish eggs and larvae, or where the predators are larvae; these cases were deleted from the analysis discussed here].

Though approximate, these conversions yield a clear pattern (see Fig. 41), confirming the hypothesis in (1). The second hypothesis was also verified, though this is not shown here.

Fig. 41 can also be used, obviously, as reference for true exceptions, e.g., gulpers (Fam. Eurypharyngidae) which can consume fish well above their own size, or filter-feeders and grazers, which consume prey that are orders of magnitude smaller than themselves.


Ursin, E. 1973. On the prey preference of cod and dab. Medd. Danm. Fisk. Havunders. N.S. 7:85-98.

Daniel Pauly


Fig. 41. Predator vs. prey length in miscellaneous fish species. See Box 29 for a discussion of this graph.

How to get there

You get to the PREDATORS table by clicking on the Biology button in the SPECIES window, the Trophic Ecology button in the BIOLOGY window and the Predators button in the TROPHIC ECOLOGY window. Note that a double-click anywhere within the row on the Predator List view will bring you to that specific record in the PREDATORS table.


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


Collette, B.B. and C.E. Nauen. 1983. FAO species catalogue. Vol. 2. Scombrids of the world. An annotated and illustrated catalogue of tunas, mackerels, bonitos and related species known to date. FAO Fish. Synop. (125):137 p.

de Luca, F. 1988. Taxonomic authority list. Aquatic Sciences and Fisheries Information System. Ref. Ser. No. 8, 465 p.

Ebert, D.A., P.D. Cowley and L.J.V. Compagno. 1991. A preliminary investigation of the feeding ecology of skates (Batoidea: Rajidae) off the west coast of southern Africa. S. Afr. J. Mar. Sci. 10:71-81.

Hardy, J.D. 1993. NODC taxonomic code links biology and computerized data processing. Earth System Monitor 4(2):1-2.

Hensley, V.I. and D.A. Hensley. 1995. Fishes eaten by sooty terns and brown noddies in the Dry Tortugas, Florida. Bull. Mar. Sci. 56(3):813-821.

Hiatt, R.W. and D.W. Strasburg. 1960. Ecological relationships of the fish fauna on coral reefs of the Marshall Islands. Ecol. Monogr. 30(1):65-126.

Mathews, F.D., D.M. Damkaer, L.W. Knapp and B.B. Collette. 1977. Food of western north Atlantic tunas (Thunnus) and lancetfishes (Alepisaurus). NOAA Tech. Rep. NMFS SSRF –706. 19 p.

Meyer, M. and M.J. Smale. 1991. Predation patterns of demersal teleosts from the Cape south and west coasts of South Africa. 2. Benthic and epibenthic predators. S. Afr. J. Mar. Sci. 11:409-442.

Randall, J.E. 1967. Food habits of reef fishes of the West Indies. Stud. Trop. Ocean. Miami 5:665-847.

Scott, W.B. and E.J. Crossman. 1973. Freshwater fishes of Canada. Bull. Fish. Res. Board Can. 184:966 p.

Tokranov, A.M. and V.V. Maksimenkov. 1995. Feeding habits of predatory fishes in the Bol’shaya River estuary (West Kamchatka). J. Ichthyol. 35(9):102-112.

Uchida, R.N. 1981. Synopsis of biological data on frigate tuna, Auxis thazard and bullet tuna A. rochei. NOAA Tech. Rep. NMFS Circular 436. FAO Fish. Synop. No. 12. 463 p.

Maria Lourdes D. Palomares and Pascualita Sa-a