Marine Fish Larvae Feeding: Formulated Diets or Live Prey?

Abstract

In the rearing of larval marine fish, any diet that reduces dependance on live prey production is of technical and economic interest. Weaning juveniles with a completely developed digestive tract to a conventional diet, (i.e., “late weaning”) can be successful in any marine fish species. For example, weaning one‐month‐old sea bass (20 mg) to the study's reference diet, Sevbar, resulted in over 85% survival (40% from hatching) and 1.25 g fish at day 90 (at 19 C) In contrast, “early weaning” of larvae to special microdiets during the first month is still difficult. The best way to reduce live prey utilization in sea bass is to wean larvae at about 3–4 mg in size (day 20). If weaning could be accomplished 15 days earlier, Artemia savings could be as high as 80%. However, this introduces risks relative to growth retardation (30% weight loss) and lower juvenile quality, including greater size variability and skeletal abnormalities. Similar results have been obtained with commercial microparticles (Fry Feed Kyowa) and experimental microbound diets (MBD) made from raw materials (alginate MBD) or preferably from freeze‐dried protein sources (zein MBD). Total replacement of live prey is still impossible in marine fish. Sea bass larvae fed formulated diets exclusively from first feeding (0.3 mg larval wet weight), or even from their second week of life onwards, exhibited low survival and poor growth. Better results can be obtained when formulated diets are used in combination with live prey from first feeding, although the optimal ratio of live prey to formulated diet is still to be specified.

Development of Biopolymers as Binders for Feed for Farmed Aquatic Organisms

“…Carrageenan containing pellets are suitable for the ayu, Plecoglossus altivellis (Teshima et al, 1982), but not for postlarval tongue sole (Cynoglossus semilaevis) (Liu et al, 2008). Both alginate and zein appear to be suitable for farming larvae of sea bass (Dicentrarchus labrax) (Person Le Ruyet et al, 1993) but not barramundi (Lates calcalifer) (Partridge & Southgate, 1999), although Lee et al (1996) previously reported that Lates calcifer larvae were able to digest both alginate and gelatine bound diets. Sodiumcarboxymethilcellulose, sodium alginate and gelatin included in feed for postlarval tongue sole (Cynoglossus semilaevis) brought about a growth similar to controls (Liu et al, 2008).…”

Improving Larval Culture and Rearing Techniques on Common Snook (Centropomus undecimalis)

“…This is a major bottleneck for larval culture, due primarily to their small size and often poorly developed digestive system (Person Le Ruyet, et al, 1993). Many marine fish larvae require motile prey organisms (Pedersen et al, 1987;Pedersen and Hjelmeland, 1988).…”

“…The SS type rotifer (Super small rotifers) ranges between 100-120 µm, which are preferred for the first feeding of fish larvae with small mouth openings (rabbitfish, groupers, and other fish with mouth openings less than 100 µm at first feeding). Those rotifers, however, are not genetically isolated from Sstrains, but are smaller than common S-strains (Person Le Ruyet, et al, 1993). The last strain was an SS rotifers from the University of Ghent, Belgium, that were genetically modified to resist warmer temperatures (above 30 ºC).…”

“…In all cases, poor results were obtained when live food was replaced completely by micro-diets. However, during the last decade, the preweaning period has been greatly reduced in many species, such as European sea bass Dicentrarchus labrax (Person Le Ruyet et al, 1993, Zambonino-Infante et al 1997. Cahu et al, (1998) reported that 35% of European sea bass larvae were fed exclusively compound diet from mouth opening.…”

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“…This is especially, relevant in sea bass larval rearing, where live food accounts for 79% of the production cost for juveniles up to 45 days old. In the first 3 months of life, live food represents 50% of the feed cost even though they constitute only 1.6% of the total dry weight of food required (Person-Le Ruyet et al, 1993). Nowadays, more studies are focused on early weaning and its effects on digestive physiology related to studies on the development of the digestive system and gastrointestinal physiology of marine fish larvae.…”