Forest fragmentation influences the diet of cichlids Apistogramma agassizii (Steindachner, 1875) and Aequidens tetramerus (Heckel, 1840) (Actinopterygii: Cichliformes) in streams of the Western Amazon

Abstract

Aims To evaluate the effects of replacing riparian vegetation with pasture in the diet of Apistogramma agassizii and Aequidens tetramerus. Methods The study was carried out in the municipality of Senador Guiomar, Acre. We sampled three streams divided into three stretches each (100 m), bordered by forest, pasture, and both forest and pasture (edge). Quarterly collections using fishnets were performed between January and October 2008. Results The species A. agassizii had a diet based on the consumption of adult insects in stretches of forest, different from the pasture environment, in which the consumption of insect larvae was higher. In the diet of A. tetramerus, the most important item was insect larvae in all environments, mainly in the pasture. We found low amplitude of trophic niche for A. agassizii in the forest environment, due to the consumption of adult insects, and for A. tetramerus in the pasture, due to the consumption of insect larvae. In the pasture areas, we found no difference between the items consumed by the species, which showed a high trophic niche overlap, influenced by the consumption of Diptera larvae. Conclusion Thus, we show that allochthonous items, such as adult insects, are food resources indicative of riparian vegetation conservation and are important for both species, mainly A. agassizii. However, this item has been replaced by autochthonous items, such as Diptera larvae, in the A. agassizii diet and become predominant in the A. tetramerus diet as the riparian vegetation deteriorates.

Reproductive aspects of the dwarf cichlid Apistogramma agassizii under captive conditions

“…A. agassizii is a species of dwarf cichlid endemic to the Amazon basin, with minimal qualitative information on its biology and ecology in its natural habitat, despite its importance in the ornamental fish trade (Anjos et al, 2009;Tribuzy-Neto et al, 2020;Mendes et al, 2021). It is found and collected throughout the floodplain of the Amazon basin and lives in all types of water, including white, black, and clear, and in degraded environments, being considered an opportunistic fish with an insectivorous tendency (Römer, 2006;Virgílio et al, 2020). Lima et al (2001) mentioned that a major threat to ornamental fish is that certain species are vulnerable to disappearance due to the lack of studies on their reproduction in captivity.…”