Feeding behaviour and digestive physiology in larval fish: current knowledge, and gaps and bottlenecks in research

Abstract

Food uptake follows rules defined by feeding behaviour that determines the kind and quantity of food ingested by fish larvae as well as how live prey and food particles are detected, captured and ingested. Feeding success depends on the progressive development of anatomical characteristics and physiological functions and on the availability of suitable food items throughout larval development. The fish larval stages present eco-morpho-physiological features very different from adults and differ from one species to another. The organoleptic properties, dimensions, detectability, movements characteristics and buoyancy of food items are all crucial features that should be considered, but is often ignored, in feeding regimes. Ontogenetic changes in digestive function lead to limitations in the ability to process certain feedstuffs. There is still a lack of knowledge about the digestion and absorption of various nutrients and about the ontogeny of basic physiological mechanisms in fish larvae, including how they are affected by genetic, dietary and environmental factors. The neural and hormonal regulation of the digestive process and of appetite is critical for optimizing digestion. These processes are still poorly described in fish larvae and attempts to develop optimal feeding regimes are often still on a 'trial and error' basis. A holistic understanding of feeding ecology and digestive functions is important for designing diets for fish larvae and the adaptation of rearing conditions to meet requirements for the best presentation of prey and microdiets, and their optimal ingestion, digestion and absorption. More research that targets gaps in our knowledge should advance larval rearing.

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“…This phenomenon is clearly stated that specific activity of amylase could be presented higher profile during larval stages and usually declines until starting of juvenile stage which is considered an indicator of pancreatic maturation in marine fish. Besides, shifting and biochemical composition of offered food and weaning could trigger amylase activity which is stimulated by glycolytic chains, glycogen, and starch content of food Zambonino Infante et al, 2008;Rønnestad et al, 2013). Additionally, it is reported that carbohydrate content of live food (6-10%) and compound diet (<12%) used for feeding larvae which might have differentially stimulated the synthesis and secretion of amylase during early ontogeny of fish larvae (Ma et al, 2005;Suzer et al, 2006bSuzer et al, , 2007aGisbert et al, 2009).…”

Total lipids content and fatty acids composition of the rotifer Brachionus plicatilis using artificial enrichments

“…As live prey organisms of suitable size and palatability, stimulate the predation of the fish larvae, resulting to a better survival and fry quality (Pousao-Ferreira et al, 2003). The nutritional value of rotifers as live feed for fish larvae was studied intensively and continuously improved, as dietary value impacted larval growth and development (Oka et al, 1980;Rønnestad et al, 2013). Several rearing trials of rotifers fed with algal species and strains in various forms (fresh, frozen, dried, frozen-dried, concentrated, frozen concentrated, etc) have been carried out in order to support the population growth and survival of the rotifer cultures as well as improve the dietary value of Brachionus plicatilis (Scott and Baynes, 1978;Yufera and Pasqual, 1983;Yamasaki et al, 1984;Lubzens et al,1995;Yufera and Navarro, 1995;Navarro and Sarasquete, 1998;Robert and Trintignac, 1997;Maruyama et al, 1997;Yoshimura et al, 1997;Tzovenis, et al, 2004;Palmtag et al, 2006;Tzovenis et al, 2009;Seychelles et al, 2009;Kotani et al, 2010).…”

Carotenoids in Aquatic Ecosystems and Aquaculture: A Colorful Business with Implications for Human Health

“…One of the biggest problems in aquaculture is related to the feeding of fish during the first larval stages when their incomplete developments results in the inability to digest some food and their small size hampers eating and swallowing of large food particles (Rønnestad et al, 2013). Appropriate feeding protocols for each species should be planned, including the amount of food offered and the periodicity of feeding, as well as the optimum temporal sequence for different prey types during development when live feed is provided (Rønnestad et al, 2013).…”

“…Appropriate feeding protocols for each species should be planned, including the amount of food offered and the periodicity of feeding, as well as the optimum temporal sequence for different prey types during development when live feed is provided (Rønnestad et al, 2013).…”