Feeding behavior of the cichlid,Sarotherodon galilaeum: selective predation on Lake Kinneret zooplankton

In laboratory feeding trials, we analyzed the feeding behavior and selectivity of the cichlid, Sarotherodon galilaeum, for zooplankton prey from Lake Kinneret, Israel. The feeding behavior was dependent on fish size. Fish less than 20 mm SL fed on zooplankton as obligate particulate feeders. Fish from 20 to 42 mm SL fed either as particulate feeders or as filter feeders. Fish larger than 62 mm SL fed as obligate filter feeders. Particulate-feeding fish were size selective and had highest feeding electivities for large-sized zooplankton species. Filter-feeding fish had highest feeding electivities for zooplankton species with poor escape ability. In general, S. galilaeum predation pressure would be greatest on Ceriodaphnia reticulata, a large-bodied and easily captured species which is selected by both particulate-feeding and filter-feeding fish.     

Prey use of wetland benthivorous sunfishes: ontogenetic, interspecific and seasonal variation

The intensity of competitive interactions between fishes is partly determined by prey use and ontogenetic niche shifts. In a wetland where distinct habitat shifts are missing we compared prey use of three generalist benthivorous sunfishes to look for evidence of ontogenetic, interspecific, and “seasonal” variation in prey composition. Diet analysis revealed evidence of diet ontogeny in warmouth (Lepomis gulosus, 30–152 mm standard length, SL), but not in bluespotted sunfish (Enneacanthus gloriosus, 30–47 mm SL) or dollar sunfish (Lepomis marginatus, 30–60 mm SL). Bluespotted and dollar sunfishes consumed small dipteran and amphipod prey and had similar diets in both seasons suggesting a potential for strong interspecific competition. In the dry season, warmouth shifted from using smaller insect prey to larger decapod and fish prey with increasing size. This shift to prey types that were little used by the other species reduced dietary niche overlap with the other sunfishes. After drought and re-flooding (in the wet season), decapods and small fish were less abundant in the wetland and the warmouth ontogenetic shift was less distinct. When matched for gape width, prey composition differed between warmouth and both dollar and bluespotted sunfishes in the wet season, suggesting differences in sunfish foraging modes, but prey use differences were less clear in the dry season when prey were abundant. Both warmouth ontogenetic diet shifts and seasonal variation in prey use (probably mediated by prey abundance) had strong influences on diet overlap and therefore the potential for intra- and interspecific competition between sunfishes in this wetland ecosystem.     

Diet-shifts by an estuarine goby (Pomatoschistus microps) in the face of variable prey availability

Ontogenetic shifts in diet provide a mechanism for maximising fitness throughout development and are common where predators exhibit large increases in size. In order to maximise their fitness throughout development, benthic feeding fish can show diet-shifts that centre on the transition from meiofaunal to macrofaunal prey. Here we assessed whether such a shift was influenced by natural variation in prey-size availability by comparing the sizes of prey consumed by naturally foraging common gobies (Pomatoschistus microps). We tested explicitly for the presence of an ontogenetic shift by analysing the length of prey consumed and an index for prey importance for gobies of different lengths. We also tested the match between actual diets and those predicted by a foraging model. The goby size at which the diet-shift occurred was consistent among locations that differed in their availability of prey and through temporal changes in densities and types of prey. The mean sizes of ingested prey increased for gobies > 35 mm in length and the relative importance of macrofauna increased at 30 mm. The foraging model predicted that gobies > 30 mm would eat larger prey than would smaller gobies which differed from the observed changes in prey-size at 35 mm. Availability of prey did not appear to influence the lengths at which gobies changed diet but did affect the size of prey taken after the diet-shift. A relatively large abundance of large-bodied chironomids at two sites was reflected in the mean size of prey consumed by gobies > 30 mm at these sites. Our study indicates that intrinsic mechanisms can be more important than fluctuating environments in determining prey-choice and shifts in diet, although for the common goby, variability in prey-size may have implications for prey-choice later in ontogeny.     

Short-term foraging patterns of individual cornetfish, Fistularia commersonii, based on stomach content analysis

Stomach contents of 75 specimens of the cornetfish Fistularia commersonii, collected in shallow water off Kuchinoerabu-jima Island, southern Japan were analyzed. Many fish contained multiple prey. The prey were mostly fish, grouped into two types, pelagic and reef fishes. The size of prey increased as the size of F. commersonii increased. All the small individuals (<50 cm SL) had fed on only small reef fish. However, most of the large individuals (>50 cm SL) had fed on either prey type. Both pelagic and reef fishes usually occurred simultaneously in shallow water, suggesting that most of the large cornetfish may selectively hunt either type of prey. Received: February 27, 2001 / Revised: September 11, 2001 / Accepted: October 10, 2001     

Ontogenetic dietary shifts and morphological correlates in striped mullet,Mugil cephalus

Synopsis Ontogenetic dietary shifts are well studied in fishes. However, these shifts are rarely correlated with habitat and morphology. This study investigates: (1) ontogenetic dietary changes in mullet; and if dietary shifts do occur (2) whether they are correlated with feeding location, feeding behavior and/or feeding morphology. Stomach contents from eight size classes, each with 25 individuals, were analyzed using a gravimetric sieve fractionation procedure, Czechanowski's Quantitative Index and cluster analysis. Core samples (5 mm deep) were also analyzed in the same manner. Morphological characters were measured to detect differences among the size classes. Cluster analysis showed three distinct trophic units for Mugil cephalus in Cross Bayou: (1) 20.0 mm standard length — 30.0 mm SL; (2) 30.0 mm SL — 40.0 mm SL; and (3) 40.0 mm SL — > 100 mm SL. Comparison of the gut contents to the sediment contents for each size class showed an increase in similarity as the fish grew. Mullet gut contents from fish 20–25 mm SL were only 45% similar based on the weights of the prey items to the sediment subsample prey items, while stomach contents from fish > 100 mm SL were 84% similar to the sediment subsample contents. Gill raker length and interraker spacing of four gill arches were allometric with respect to standard length. Prey particle size within size classes appeared to be more correlated with feeding behavior than gill interraker spacing because smaller particles than predicted by the interraker spacing were ingested. It is suggested that smaller fish may be browsing more selectively than larger fish which graze.     

Seasonal variation of food and feeding in burrowing goby <Emphasis Type="Italic">Parapocryptes serperaster</Emphasis> (Gobiidae) at different body sizes

Diet composition and feeding habits of the burrowing fish Parapocryptes serperaster were investigated on different fish sizes across dry and wet seasons in the Mekong Delta, Vietnam. The gut length was positively related to fish length; the gut length was 1.57 ± 0.30 times the total length, which is in the range for omnivore (1–3). Detritus, algae and copepods were the main food items in the foregut. The diet composition showed seasonal and intraspecific variations in all fish sizes. The diet diversity varied with fish size and the dry-wet season pattern, and small fish had a higher diet diversity than large fish. The diet evenness index and Costello graphic analysis indicate that this goby is a generalist feeder and feeds mainly on detritus, followed by diatoms, and could obtain food from the bottom and the water column. The feeding intensity of P. serperaster was higher in the wet season than in the dry season, but was not significantly affected by fish size. The P. serperaster fed on Navicula spp. in the wet season, but on Nitzschia spp. in the dry season. The understanding of food and feeding habits of P. serperaster contributes to our knowledge on feeding adaptation of small-bodied bottom-dwelling gobies to the mud flat habitats in tropical monsoonal regions.     

Predation of zebra mussels by round gobies, Neogobius melanostomus

Preliminary gut analysis of a recent Great Lakes invader, the round goby, Neogobius melanostomus (7.0–8.4 cm), collected from the Detroit River, showed that they ate zebra mussels (58%), snails (6%), and other invertebrates (36%), including aquatic insects (Hexagenia), softshelled crayfish, and zooplankton. Because zebra mussels, Dreissena polymorpha, predominated as prey, we investigated the ability of round gobies to consume different size classes of zebra mussels. In laboratory experiments, we examined feeding preferences of three size classes of round gobies (5.5–6.9 cm; 7.0–8.4 cm; 8.5–10.3 cm standard length) on four different size classes of zebra mussels (6.0–9.9 mm, 10.0–12.9 mm, 13.0–15.9 mm, 16.0–18.9 mm). All sizes of round gobies ate zebra mussels < 10.0 mm. Only the largest size class of round gobies ate larger zebra mussels (10.0–12.9 mm) when all prey sizes were presented. The association between the total mass of zebra mussels available and the amount consumed by round gobies increased positively up to about 6.5 g of available mussels and then levelled off. Round gobies consumed an average of 1.0 g of mussels in 24 h. There was a significant positive relationship between gape size and standard length of round gobies. Although larger round gobies (over the size range of fish in our study) are able to consume larger zebra mussels, small mussels were preferred. Our findings suggest that the preference of small zebra mussels by round gobies has the potential to alter the size structure of zebra mussel populations. This revised version was published online in July 2006 with corrections to the Cover Date.     

Feeding convergence in South American and African zooplanktivorous cichlids Geophagus brasiliensis and Tilapia rendalli

Synopsis Acará, Geophagus brasiliensis, and red-breasted bream, Tilapia rendalli, are important planktivorous cichlids in southern Brazilian lakes and reservoirs. In laboratory experiments, I quantified behavior and selectivity of different sizes of these two fish feeding on lake zooplankton. Feeding behavior depended on fish size. Fish < 30 mm were visual feeders. Fish 30–50 mm either visually fed or pump-filter fed depending on zooplankton size. Fish > 70 mm were pump-filter feeders. Replicate 1 h feeding trials revealed that, as the relative proportions of prey changed during an experiment, acará (30–42 mm, standard length) and tilapia (29–42 mm) shifted from visual feeding on large evasive copepods to filter feeding on small cladocerans and rotifers. Electivity and feeding rate increased with prey length, but were distinct for similar-sized cladocerans and copepods. Visual/filter-feeding fish had lowest electivities for small and poorly evasive rotifers and cyclopoid nauplii. They fed non-selectively on cyclopoid copepodites, had intermediate electivities for calanoid nauplii and small cladocerans, and had highest electivities for large cladocerans, cyclopoid adults, and calanoid copepodites and adults. Although belonging to different cichlid genera and native to South America and Africa, respectively, acará and red-breasted bream (= congo tilapia) exhibited similar selectivity for zooplankton. Apparently, few stereotyped feeding behaviors have evolved during the acquisition of microphagy in fish. Shift in feeding modes allows these two species to optimally exploit the variable and dynamic patchy distribution of planktonic resources.     

Effects of season and body-size on the distribution and diet of the Iberian chub Leuciscus pyrenaicus in a lowland catchment

Seasonal and ontogenetic variations in space and food use by Leuciscus pyrenaicus were analysed in a Portuguese lowland catchment. Large fish occurred mostly in deep permanent-flowing sites whereas small fish occurred mostly in the shallowest intermittent-flowing site. No seasonal or size-related changes in feeding intensity were found, but the diet changed both across seasons and throughout ontogeny. The diet was dominated by aquatic prey over all seasons, but during winter and summer more plant material and terrestrial prey, respectively, were eaten. Throughout ontogeny fish shifted from soft-bodied to hard-shelled prey and decreased animal prey breadth. Mean prey size increased with fish size but the prey size spectrum was more variable for medium-sized fish than for either small or large fish. It is suggested that: (i) large fish avoid shallow drying areas owing to the risk of mortality, either by thermal and respiratory stresses or increased predation by mammals and birds; (ii) seasonal changes in diet are a response to differences in prey availability; and (iii) morphological constraints, prey handling costs and habitat partitioning are responsible for size-related changes in diet.     

Diet and feeding habits of Economidichthys pygmaeus (Perciformes: Gobiidae) in Lake Pamvotis,NW Greece

The purpose of the study was to define the diet composition, feeding preferences, seasonal, size and sex related changes in diet, feeding strategy and diel cycle of Economidichthys pygmaeus. Important features of the overall feeding patterns of the goby include (i) feeding activity, (ii) bottom habits and (iii) consumption of food items to identify the dietary breadth. Stomach contents of 533 specimens, 13.42–48.65 mm total length (TL), collected by hand net (2 mm mesh size) from October 2006 to September 2007 were analyzed. The percentage of 76 empty stomachs (14.26%) did not vary significantly with season. The food composition suggested that the goby is a carnivorous fish. Prey items identified in the stomachs belonged to four major groups: Crustaceans, Insects, Mollusca and Plants. Copepods were the most important (%IRI = 57.51), especially in fish larger than 23 mm TL. Chironomids (%IRI = 43.23) constituted the main prey for fish <23 mm TL. Diet composition showed little seasonal variation. Copepoda dominated the diet in autumn and winter (43.4%; 82.4%) and were replaced by Chironomidae larvae in spring (39.7%) and summer (47.7%). During the reproductive season, large males show a narrow food spectrum as opposed to large females, reflecting the different activity pattern exhibited by males and females during the breeding season, since the former supports parental care. According to the modified Costello graphical method, specialist individuals form the goby population that feeds on two preferential prey types (e.g. Copepods, Chironomids). Nevertheless, they consume some occasional prey (e.g. Cladocera, Insects, Gastropods). The species foraged chiefly at night and early morning, during lower light intensity. The highest feeding activity recorded at night (02.00 hours) and during early morning (08.00 hours) could be related to the cryptic behaviour displayed by the species.     

Effects of season, sex and body size on the feeding ecology of turtle-headed sea snakes (Emydocephalus annulatus) on IndoPacific inshore coral reefs

In terrestrial snakes, many cases of intraspecific shifts in dietary habits as a function of predator sex and body size are driven by gape limitation and hence are most common in species that feed on relatively large prey and exhibit a wide body-size range. Our data on sea snakes reveal an alternative mechanism for intraspecific niche partitioning, based on sex-specific seasonal anorexia induced by reproductive activities. Turtle-headed sea snakes (Emydocephalus annulatus) on coral reefs in the New Caledonian Lagoon feed entirely on the eggs of demersal-spawning fishes. DNA sequence data (cytochrome b gene) on eggs that we palpated from stomachs of 37 snakes showed that despite this ontogenetic stage specialization, the prey comes from a taxonomically diverse array of species including damselfish (41 % of samples, at least 5 species), blennies (41 %, 4 species) and gobies (19 %, 5 species). The composition of snake diets shifted seasonally (with damselfish dominating in winter but not summer), presumably reflecting seasonality of fish reproduction. That seasonal shift affects male and female snakes differently, because reproduction is incompatible with foraging. Adult female sea snakes ceased feeding when they became heavily distended with developing embryos in late summer, and males ceased feeding while they were mate searching in winter. The sex divergence in foraging habits may be amplified by sexual size dimorphism; females grow larger than males, and larger snakes (of both sexes) feed more on damselfish (which often lay their eggs in exposed sites) than on blennies and gobies (whose eggs are hidden within narrow crevices). Specific features of reproductive biology of coral reef fish (seasonality and nest type) have generated intraspecific niche partitioning in these sea snakes, by mechanisms different from those that apply to terrestrial snakes.     

Feeding habits and ontogenetic diet shifts of hairtail, Trichiurus margarites, in the Beibu Gulf of the South China Sea

The monthly and ontogenetic variations in diet of hairtail Trichiurus margarites Li (1992) [20] (Perciformes, Trichiuridae) were examined in the Beibu Gulf of the South China Sea from October 2008 to September 2009. Stomachs of 666 hairtail ranging in size from 121 mm to 561 mm pre-anal length (PL) were sampled monthly from commercial fish catches. Fish were the primary prey, with Decapterus maruadsi (Perciformes, Carangidae) averaging 23% by number, 34% by weight, and 49% by Index of Relative Importance (IRI). Other important prey in the diet included the small benthic fish, Bregmaceros rarisquamosus and Bregmaceros nectabanus (Gadiformes, Bregmaceroridae) and the decapod shrimp, Acetes chinensis, with IRI percentages of 8%, 4%, and 3%, respectively. Low rates of cannibalism and predation on 30 additional species of prey were observed. Trophic diversity (Brillouin Index, H_z) was moderate throughout the year. Mean feeding intensity (Repletion Index, RI) varied considerably by month and increased with the gonad maturity stages of hairtail; conversely, the proportion of empty stomachs decreased with maturity stages, from 60.9% empty at Stage I to 41.6% empty at Stage VI. Prey weight and numbers differed significantly among the 14 PL size classes and increased with body size. Cluster analysis of prey IRI values also indicated differences in the feeding habits of hairtail by size class. Understanding the monthly and ontogenetic changes in hairtail diet may assist in the development and improvement of marine ecosystem modeling for the Beibu Gulf, South China Sea.     

北部湾带鱼的摄食习性

2008年8月至2009年9月,对北部湾带鱼逐月渔获物胃含物进行鉴定和统计分析,研究其摄食习性.结果表明：北部湾带鱼捕食种类包括鱼类、头足类、底栖甲壳类以及浮游动物等,属于广食性动物.优势种类有少鳞犀鳕(37.99%)、蓝圆鲹(16.42%)和中国毛虾(10.03%).蓝圆鲹和尖吻小公鱼全年在全湾带鱼的食物中均有出现,是重要的饵料指标种类.摄食强度与饱满指数的季节差异十分显著(P<0.001),食物多样性无显著季节性差异(P>0.05),秋季最高,全年平均为1.97.聚类分析表明,北部湾带鱼在达到50%性成熟肛长值(190 mm)时,饵料由幼鱼的以小型浮游动物、中上层鱼类及甲壳类为主向成鱼的以较大型鱼类和头足类为主转换.     

Diet and prey selection in larval and juvenile Japanese anchovy Engraulisjaponicus in Ariake Bay, Japan

We studied the diet of larval and juvenile Japanese anchovy Engraulis japonicus in the upper Ariake Bay, Japan. Diet was analyzed by examining the digestive tracts; feeding intensity, proportion of empty guts, and prey selectivity were calculated. Anchovy density was negatively influenced by temperature and positively by salinity and prey density. Diet was dominated by Acartia omorii, which was positively selected with two other copepods, Calanus sinicus and Pseudodiaptomus marinus. In contrast, Oithona davisae was highly dominant in the environment but was absent in anchovy guts; thus, this copepod was negatively selected, with two others, Tortanus derjugini and Sinocalanus sinensis. Overall, larger prey were positively selected and smaller ones were negatively selected; value of electivity index correlated negatively with prey size. Larvae [<18 mm of standard length (SL)] showed significantly lower feeding intensities and higher rates of empty guts than juveniles (≥18 mm SL). In juveniles, feeding intensity increased steadily as the fish grew in size, with a corresponding reduction in empty guts. Feeding intensity correlated positively and empty gut correlated negatively with fish size. We suggest that larger prey are important diets for postlarval Japanese anchovy in Ariake Bay.     

北部湾带鱼的摄食习性

2008年8月至2009年9月,对北部湾带鱼逐月渔获物胃含物进行鉴定和统计分析,研究其摄食习性.结果表明：北部湾带鱼捕食种类包括鱼类、头足类、底栖甲壳类以及浮游动物等,属于广食性动物.优势种类有少鳞犀鳕(37.99%)、蓝圆鲹(16.42%)和中国毛虾(10.03%).蓝圆鲹和尖吻小公鱼全年在全湾带鱼的食物中均有出现,是重要的饵料指标种类.摄食强度与饱满指数的季节差异十分显著(P<0.001),食物多样性无显著季节性差异(P>0.05),秋季最高,全年平均为1.97.聚类分析表明,北部湾带鱼在达到50%性成熟肛长值(190 mm)时,饵料由幼鱼的以小型浮游动物、中上层鱼类及甲壳类为主向成鱼的以较大型鱼类和头足类为主转换.     

Temporal and ontogenetic variation in the diet of squid (<Emphasis Type="Italic">Loligo forbesii</Emphasis> Streenstrup) in Scottish waters

The squid Loligo forbesii is the only cephalopod species currently targeted by fisheries in the northern NE Atlantic. An active predator, it feeds primarily on fish, crustaceans and cephalopods. During 15 years since the only previous large-scale study of the diet of this species in Scottish waters, there have been substantial changes in marine fish abundances. The present study evaluates sources of variation (temporal, ontogenetic) in diet composition and prey size preferences of L. forbesii, including a comparison of contemporary (July 2006–June 2007) and historical (1990–1992) dietary datasets. Results revealed significant size-related and seasonal variation in diet composition and prey size. Teleost fish of the families Ammodytidae and Gobiidae were eaten by squid of all sampled sizes, although occurrence of gobies was generally more frequent in smaller squids, while Gadidae were eaten more frequently by larger squids. Cannibalism was also more frequent in larger squids. Compared to the 1990–1992 dataset, clupeid fish were less important in the diet of squid in 2006–2007, while the importance of gobies increased, and the size of gobies eaten also increased. The trend in gadoids differed according to the index used: their frequency of occurrence was considerably higher in 2006–2007 than in 1990–1992, but their numerical importance was slightly lower. In general, results provided little evidence that changes in the diet of L. forbesii correspond with changes in fish abundance, at least at the scales at which these are measured.     

Feeding biology of the flatfish Citharichthys spilopterus (Bothidae) in a tropical estuary of Mexico

The flatfish Citharichthys spilopterus Günther 1862 is the most common bothid in the coastal lagoons of the Gulf of Mexico. The objective of the present study was to describe the trophic biology of this species in the tropical coastal lagoon of Tampamachoco, Mexico. For the diet analysis, we used multivariate discriminant analysis and trophic niche breadth. The morphological analysis showed that the features of the bucco-pharyngeal cavity, the large stomach and the short intestine of this flatfish relate to a carnivorous habit. The overall diet showed that this species is a third-order consumer, feeding mainly on fish (52%, mainly gobies) and crustaceans (36%, mostly decapods). Diet and trophic niche breadth showed no significant differences between sexes (P > 0.1). By contrast, there were significant ontogenetic differences in the diet and trophic niche breadth, where larger C. spilopterus were almost entirely piscivorous and showed the narrowest trophic niche. As the flatfish grew in size there was a trend toward the consumption of larger prey. The importance of copepods and peracarids correlated inversely with flatfish size (P < 0.001), but fish prey correlated directly to flatfish size (P < 0.001). Likewise, there was an inverse significant correlation between niche trophic breadth and flatfish size (P < 0.005). There were also significant seasonal differences in the diet (P < 0.02), related to the availability and vulnerability of prey in the lagoon during the dry and rainy seasons. However, the trophic niche showed no significant differences between seasons. Finally, we discuss the advantages of discriminant analysis applied to evaluate differences among diets of fish groups when compared with other bivariate and multivariate techniques.     

Invasive Lionfish (<Emphasis Type="Italic">Pterois volitans/miles</Emphasis>) feeding ecology in Biscayne National Park,Florida, USA

Indo-Pacific Lionfish (Pterois volitans and P. miles) are venomous marine fishes in the family Scorpaenidae that invaded the Caribbean Sea, Gulf of Mexico, and western North Atlantic Ocean beginning in the mid-1980s. Lionfish are generalist, opportunistic predators that consume a variety of invertebrates and small reef fishes, such that the presence of Lionfish can significantly reduce reef fish abundance, diversity, and recruitment on invaded reefs. This study focused on the feeding ecology of Lionfish in Biscayne National Park (BNP), located in southeast Florida, USA. BNP consists of multiple marine habitats, including mangroves, seagrass beds, coral reefs, and limestone keys that support a diverse array of species resulting in multi-million dollar fishing and tourism industries. These habitats within BNP are at risk from the predatory impacts of invasive Lionfish. Through morphological prey identification of stomach contents, supplemented with DNA barcoding for identification of highly-digested prey items, Lionfish diet was analyzed and compared among fish sizes (immature, transitional and mature), BNP region (bay, shelf, and edge), and seasons (wet and dry). A total of 513 stomachs, containing more than 2600 prey items, were examined. We report that Lionfish in BNP fed predominantly on small reef fishes and small crustaceans, with a dietary shift from crustaceans to fishes occurring with increasing Lionfish size. Diets differed among BNP regions for medium-sized (100–179 mm) transitional Lionfish but not for large-sized (≥?180 mm) mature individuals. Furthermore, dietary differences between seasons were observed in mature Lionfish, but no seasonal differences were detected for smaller Lionfish (i.e., immature and transitional Lionfish). Based on the diet habits observed, Lionfish in BNP could have significant ecological and economic consequences for BNP and south Florida coastal habitats.     

Diet composition of greater weever,Trachinus draco (Linnaeus, 1758) captured in the eastern‐central Adriatic Sea in relation to fish size,season and sampling area

The diet compositions of greater weever, Trachinus draco, from the eastern‐central Adriatic Sea, were investigated with respect to seasons, fish size and sampling locations. Analyzed were the stomach contents of 592 specimens, total length (TL) of 9.9–31.2 cm, collected by commercial bottom trawls from January to December 2008. The frequency of empty stomachs varied significantly with the season (43.3% maximum during winter; 6.8% minimum during summer). Prey items identified in the stomachs belonged to seven major taxonomic groups: Bivalvia, Cephalopoda, Decapoda, Mysidacea, Isopoda, Amphipoda and Teleostei. Decapods were the most important prey (%IRI = 72.8) followed by teleosts (%IRI = 16.4) and mysids (%IRI = 15.0); other prey groups were only occasionally ingested. Diet composition showed little seasonal variation; decapods were the most important prey in all seasons. Fish size was the most important factor influencing the composition of the diet. Small individuals (<15 cm TL) fed primarily on small crustaceans (mysids), whereas larger fish consumed bigger prey, such as decapods, teleosts and cephalopods. There was high dietary similarity between sampling locations. Based on the diet, greater weever can be a considered a generalistic predator.