On the methodology of feeding ecology in fish

Abstract

Irrespective of their way of feeding, say it be 'passive' or 'active', fishes are ultimate predator of phytoplankton (after Begon et al. 2006), zooplankton or small fishes. In all groups of fishes, the mode of predation (e.g. 'hang and wait' or 'move and hunt') has great contribution to successful feeding, mostly in preference and selection of specific food items from a diverse group of resources. Such 'preferential feeding' has rare possibility to be a linear ecological function, rather, it is a kind of non-linear behaviour, across many gradients scaled on time (e.g. ontogenic shifting of fish), space (e.g. across depth or temperature), morphology (e.g. prey morphology or predator size) or other biological attributes.Feeding ecology, in animal science, defines a relationship where the animal adopts a strategy for optimum foraging of or predation on its preferred food. As a result of their complex life history, food preferences or trophic selection by fishes play crucial role in their development, growth and survival, which often shifts from one type of food or trophic level to other during ontogeny. Three most generalised ontogenic stages of fishes are larval, juvenile and adult. For migratory fishes, parr and smolt are additional morpho-physiological ontogenic stages. These ontogenic forms compete in water for feeding within the population itself and also with co-habiting species. Under such situation, similar to other vertebrates, fishes tend to fit through niche apportionment with minimum diet overlap to avoid unruly competitive outcomes. Therefore, how fishes 'optimally manage' to eat their preferred prey during ontogenic shifting as well as under high competitive pressure and remain cohesive to an ecologically sustainable model is the key criterion of their feeding ecology, and coincidently, sparks micro-evolution.Feeding ecology in fishes questions how fish selectively ingest some food organisms over others in the aquatic On the methodology of feeding ecology in fish EJE 2016 Feeding ecology explains predator's preference to some preys over others in their habitat and their competitions thereof. The subject, as a functional and applied biology, is highly neglected, and in case of fish, a uniform and consistent methodology is absent. The currently practiced methods are largely centred on mathematical indices and highly erroneous because of non-uniform outcomes. Therefore, it requires a relook into the subject to elucidate functional contributions and to make it more comparable and comprehensive science. In this article, approachable methodological strategies have been forwarded in three hierarchical steps, namely, food occurrence, feeding biology and interpretative ecology. All these steps involve wide ranges of techniques, within the scope of ecology but not limited to, and traverse from narrative to functional evolutionary ecology. The first step is an assumption-observation practice to assess food of fish, followed by feeding biology that links morphological, histological, cytological, bacteriological o...

Seasonal and depth variations in diet composition and dietary overlap between three native killifish of an emblematic tropical-mountain lake: Lake Titicaca (Bolivia)

“…According to Monroy et al, (2014), O. agassizii is an omnivorous species, and like other Cyprinodontiform species (Kalogianni et al , 2010; Alcaraz et al , 2015) it is not possible to generalize the feeding pattern for this species throughout the lake without considering other influencing factors (Saikia, 2016; Yoğurtçuoğlu et al , 2018). A clear influence of seasonality and depth was observed in the results, which has influenced by feeding habits changing the proportions and importance of the prey (Table 4).…”

“…Therefore, there is a niche overlap and competition for food resource are very likely, however there are no studies that prove this hypothesis. It is well known that feeding is a non-linear behaviour with many scaled gradients, such as time (i.e., time of year), space (i.e., change through depth), morphology (i.e., morphology of the prey or size of the predator) or other biological attributes (Saikia, 2016).…”

pH and Temperature Dependent Gut Enzyme Niche in a Stomachless Herbivorous Freshwater Fish <i>Amblypharyngodon mola</i> (Hamilton, 1822)

“…Digestion is a fundamental process in the metabolism of animals because it determines the availability of nutrients needed for all biological concerns where digestive enzymes play a key role [1]. In case of fish, Saikia [2] suggested enzyme assay from gut as a more convincing way to explain the qualitative selection of feeds in the environment. In all aquatic species including fish, digestive enzyme activity serves as a good indicator of their feeding ecology and trophic niche in natural conditions [3].…”

Problems of Using Molecular-Genetic Methods for the Study of Fish Feeding

“…Анализ содержимого желудков является необходимой частью исследований, посвященных вопросам экологии рыб. Несмотря на большое разнообразие существующих подходов и методов исследования питания рыб, они продолжают активно развиваться и совершенствоваться [1][2][3]. Молекулярно-генетические методы исследования содержимого желудков успешно применяются для идентификации кормовых объектов рыб [4][5][6], в том числе и байкальских [7].…”