Recent
developments in the application of live feeds in the freshwater ornamental
fish culture
L. Chuan Lim, Ph. Dhert,
P. Sorgeloos
Aquaculture, 227(1-4): 219-231
Abstract:
The industrial development of freshwater ornamental
fish culture has been hampered by the lack of suitable live feeds for
feeding the fish at the various production stages. This paper reports the
recent developments in the applications of the freshwater rotifers (Brachionus
calyciflorus), Artemia nauplii, decapsulated Artemia cysts
and on-grown Artemia in the freshwater ornamental fish culture.
Results demonstrate that the rotifers are an ideal starter feed for dwarf
gourami (Colisa lalia), a typical freshwater ornamental fish species
with larvae that are too small to ingest Artemia nauplii or Moina
at its first feeding. Compared with the conventional yolk food, the use of
rotifers as a starter feed significantly improves the growth and survival of
the gourami larvae (Days 2–12), and the beneficial effects are extended to
the subsequent Artemia-feeding phase (Days 13–32). The freshwater
rotifers and Artemia nauplii are also useful in raising Discus larvae
in the absence of their parents, which would eliminate the risk of larvae
being eaten by the parent fish. Work on decapsulated Artemia cysts
indicates that the cysts could be used as a substitute for Artemia
nauplii or Moina in freshwater ornamental fish culture. The fry of
all the five common ornamental fish species tested (guppy Poecilia
reticulata, molly Poecilia sphenops, platy Xiphophorus
maculatus, swordtail Xiphophorus helleri and neon tetra Hyphessobrycon
herbertaxelrodi) could readily feed on the decapsulated cysts, and their
performances in terms of stress resistance, growth and survival are
comparable to or better than those fed on Artemia nauplii or Moina.
A culture system for production of on-grown Artemia has also been
developed specifically for the use in freshwater ornamental fish farms. The
system, using diluted artificial seawater of 20 ppt for culture, has a mean
production rate of 3 kg/m3 of water in a 12-day cycle and a
production capacity of 8 metric tons of on-grown Artemia a year. With
the system, farmers could produce any specific size of on-grown Artemia
of up to 5 mm to suit the age and size of their fish, by varying the time of
harvesting. This characteristic, coupled with the use of bioencapsulation
technique to enhance the quality of the on-grown Artemia, would make
the organism an ideal nursery diet for freshwater ornamental fish. All these
results show that the live feeds used in marine foodfish hatchery could be
applied to freshwater ornamental fish culture to improve their performance.