Larval Fish Nutrition and Rearing Technologies: State of the Art and Future (pp. 113-148)
Authors: (Jian G. Qin, School of Biological Sciences, Flinders University, Australia)
Abstract: Marine finfish larviculture techniques have been quickly developed in the past two
decades. Although hatchery production technology still follows similar protocols
worldwide, feeding regimes and culture systems have been greatly modified to improve
hatchery performance and efficiency. Marine fish larvae are reared more often in green
water intensive systems than in clear water systems, while extensive culture is less
commonly used. The use of live food organisms, especially at first feeding, is still
obligatory in most marine fish larvae mass-culture. Rotifers Brachionus spp. and brine
shrimp Artemia nauplii are the main live food items for early life stages of the major
finfish species, with inert feed provided at a later stage. Super-intensive rotifer culture
using algal paste has improved cost-effectiveness of hatchery production, whereas
Artemia nauplii have been used as biocapsules to deliver vitamins and a variety of
nutrition (e.g., EPA, DAH and ARA) from different sources. Recently, the use of
copepods and cladocerans as live food has been explored. However, low production of
copepods is the major hurdle of mass production, but there is a growing interest in using
saline water cladocerans as live food in hatchery. Until recently, it is considered
impossible to feed most newly hatched marine fish species with a compound diet.
Substituting a compound diet for live prey is performed several weeks after hatching,
depending on the species. Ontogenetic studies suggest that most digestive enzymes are
present in young larvae, but the quantity is not sufficient to digest formulated feed.
Therefore, it is essential to provide live feed for the first feeding of marine finfish
species. Weaning of fish larvae to inert feed at a later stage of development is easily
achieved by co-feeding inert feed with live food because live food organisms consumed
by the larvae assist the digestion process by donating their digestive enzymes to the gut
of fish larvae. In larviculture rearing, high mortalities are likely to occur during the diet
transition from endogenous to exogenous nutrition and the period of weaning, and
cannibalism could contribute greatly to mortality when great size heterogeneity exists.
Reduction of larval deformity is a challenge in some fish species and further
understanding of the role of nutrition in fish development, especially at the molecular
level will allow improving the quality of hatchery reared larvae.
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