Diet and food consumption of the pearl cichlid Geophagus brasiliensis (Teleostei: Cichlidae): relationships with gender and sexual maturity

Abstract

Despite the importance of the pearl cichlid Geophagus brasiliensis for the aquarium fish trade worldwide and its wide distribution, many aspects of its biology, such as the relationships between its feeding ecology and reproductive behavior, are not fully understood in natural conditions on its native habitat. In this paper, we investigated its diet focusing on how differences in diet and food consumption are related to differences in gender and sexual maturity. The digestive tract of each individual was dissected and had its content analyzed, whereas each gonad was microscopically analyzed to determine gender (male/female) and sexual maturity (immature/mature). A total of 28 females and 31 males were analyzed. Mature individuals were more common than immature specimens both for males (64.50%) and females (64.30%). The analysis of 52 individuals with non-empty digestive tracts revealed a diet comprised of 27 items. According to the Index of Alimentary importance (%IAi), the most important food items in the diet were Gastropoda (37.30%), fragments of vascular plants (15.16%), detritus (10.14%), Amphipoda (9.24%), and fish scales (6.29%). Mature males had more empty stomachs (65.00%) when compared to immature males (27.27%) and immature (55.56%) and mature females (40.00%). Also, mature females seemed to have more food consumption (greater mean values of total volume) in their digestive tracts than mature males. Some hypotheses are proposed in order to distinguish if this gender-based difference in food consumption in mature individuals of the pearl cichlid could be associated with the development of primary and secondary sexual characteristics or with asymmetrical time invested in parental care activities.Apesar da sua ampla distribuição e importância para o comércio aquariofilista, muitos aspectos da biologia do cará Geophagus brasiliensis no seu habitat natural, como a relação entre sua ecologia alimentar e comportamento reprodutivo, ainda não são bem conhecidos. Nesse trabalho foi investigada sua dieta, enfocando como as diferenças na dieta e no consumo alimentar estão relacionadas ao sexo (macho/fêmea) e a maturidade (imaturo/maturo). O trato digestório de cada indivíduo foi dissecado e teve seu conteúdo analisado, enquanto cada gônada foi analisada microscopicamente para determinar o sexo e a maturidade. Um total de 28 fêmeas e 31 machos foram analisados. Indivíduos maturos foram mais comuns do que espécimes imaturos, tanto para machos (64,50%) quanto para fêmeas (64,30%). A análise de 52 indivíduos com alimento no trato revelou uma dieta composta por 27 itens. De acordo com o Índice de Importância Alimentar (%IAi), os itens alimentares mais importante na dieta foram Gastropoda (37,30%), fragmentos de plantas vasculares (15,16%), detrito (10,14%), Amphipoda (9,24%) e escamas de peixe (6,29%). Machos maturos tiveram mais estômagos vazios (65,00%) quando comparados com machos imaturos (27,27%) e fêmeas imaturas (55,56%) e maturas (40,00%). Além disso, fêmeas maturas apresentaram maior consumo de alimentos (val...

Metazoan parasites of Geophagus brasiliensis (Perciformes: Cichlidae) in Patos lagoon, extreme south of Brazil

“…Cercariae are probably released from gastropods during periods of higher temperatures, thus resulting in accumulation of the parasites in colonization processes that occur during these higher-temperature periods. The fact that gastropod mollusks comprise the main component of the diet of G. brasiliensis in the Patos/Mirim lagoon system may have contributed to these values (BASTOS et al, 2011). Moreover, the same authors showed that significant variation in the diet occurs, according to the host's maturity stage.…”

“…However, they do not eliminate eggs, and fish are infected through ingestion of these mollusks. Thus, the transmission of this trematode must be associated with ingestion of gastropod mollusks, which are one of the main components of the diet of G. brasiliensis in the Patos/Mirim lagoon system (BASTOS et al, 2011).…”

“…However, this characteristic, as well as marked differences in behavior and size (length and weight) between males and females, is reflected in the composition and mean value of their food consumption. In addition, for G. brasiliensis in the Patos/Mirim lagoon system, gastropods are the most important component of their diet (40.64% among adult males and 35.55% among adult females), with important variations in diet relating to the stage of maturity of this host (BASTOS et al, 2011). In Brazil, studies on helminths parasitizing G. brasiliensis have been reported in the Rio de Janeiro (PARAGUASSU et al, 2005;AZEVEDO et al, 2006;CARVALHO et al, 2010) Parana (BELLAY et al, 2012.…”

Environmental assessment in tropical streams by using abundance-biomass curves and W index in fish assemblages

“…The species more correlated with the urban (impacted) streams were those suited to live in siltation (a condition derived from low canopy cover and representative of low mesohabitat diversity), such as H. ancistroides (Casatti et al, 2005), I. schubarti (Severo-Neto et al, 2015), andH. strigaticeps (Jepep et al, 2007), with high feeding plasticity (impacted streams are frequently recorded as food resource restricted), like R. quelen (Gomiero et al, 2007), G. inaequilabiatus (Hahn et al, 2004), G. brasiliensis (Bastos et al, 2011), Bryconamericus iheringii (Oliveira & Bennemann, 2005;Oricolli & Bennemann, 2006), A. lacustris (Bennemann et al, 2005, under A. altiparanae), and O. paranensis (Abelha et al, 2012), adapted to feed on organic detritus (a typical food resource in impacted streams), as H. ancistroides and H. strigaticeps (Pagotto et al, 2011), and with high reproductive plasticity, as S. marmoratus (Favorito et al, 2005). All these species are adapted to use scarce alimentary, shelter, and reproductive resources, as appears to be the case here.…”

The surprising "B-side": description of a new foraging tactic for the pearl cichlid, Geophagus brasiliensis, in a coastal stream of the Atlantic Forest

“…Presenting diurnal activity and visual orientation (Sabino & Castro 1990), G. brasiliensis feeds on a wide variety of items, preferring benthic resources such as molluscs, vascular plants, crustaceans, fish scales, insects, among others (Nomura & Carvalho 1972, Sabino & Castro 1990, Abelha & Goulart 2004. Its high trophic plasticity and opportunism allow the exploitation of different resources and this species is usually classified as an omnivore (Sabino & Castro 1990, Arcifa & Meschiatti 1993, Dias et al 2004, Moraes et al 2004, Gomiero & Braga 2008, Bastos et al 2011), although differences in prey availability across study sites and conceptual approaches may lead G. brasiliensis to a variety of trophic preferences that include detritivory (e.g., Meschiatti 1995), insectivory (e.g., Ribeiro et al 2014) or even benthivory (e.g., Nunes et al 2014). However, the diversified foraging behaviour known for G. brasiliensis is usually based and inferred from the analysis of stomach contents, thus limiting the understanding of how occurs the ingestion of prey hidden under structures or adhered to objects such as leaves, wood twigs, and tree barks.…”