Limited
water exchange production systems for freshwater
ornamental fish
Lena Asano1, Harry Ako1, Eri Shimizu1 &
Clyde S Tamaru2
Abstract
Two biofilter designs and a control were tested
in triplicate to determine if inexpensive
bioremediation devices could increase production
and decrease water use on ornamental fish
farms in Hawaii. Koi (Cyprinus carpio L.)
were used as the model species and the experiment
was conducted outdoors in greenwater. When
fish density was 9.7 kg per 2.08 m3 and they
were eating 125 g day-1, the 20 L trickle
filters were able to maintain acceptable water
quality. Tanks with the same size submerged
filters suffered significantly lower dissolved
oxygen levels compared with tanks with trickle
filters and control tanks with no biofilters
exhibited significantly higher nitrite-nitrogen
(about 20 mg L-1) and nitrate levels (about
400 mg L-1). As typical ornamental fish weigh
3 g, the trickle biofilter system described
here can produce 1.55 fish L-1 (compared with
the industry standard 0.25 fish L-1) and use
very little water other than the water originally
in the tanks.
Effect
of feeding guppy fish fry (Poecilia reticulata)
diets in the form of powder versus flakes
Sheenan Harpaz1, Tatiyana Slosman1 & Ran
Segev2
Abstract
The effects of feeding guppy (Poecilia reticulata)
fry a diet offered as either powder or flakes
on their growth and survival were tested over
a period of 8 weeks. The results show that
the growth of both male and female fish was
considerably enhanced when the diet was presented
in the form of a finely ground powder compared
with a flake form. Final average weights of
fish given a diet containing the exact same
ingredients (44.9% protein and 6.1% fat),
from the same batch of raw materials in the
powdered form were 280.0±12.1 mg compared
with 114.6±19.9 mg for the diet given
in the form of flakes. In a diet that had
a higher fat level (45.1% protein and 10.6%
fat), the difference in final weight attained
was even more dramatic: 303.9±16.7
mg for the powder-fed fish compared with 92.6±12.5
mg for the flake-fed fish. The coefficient
of variance in the fish fed a flake diet was
significantly higher than that exhibited in
the treatments fed the powder feed. The ability
of the fish to consume the food in a rapid
manner, preventing leaching of vital nutrients
from the feed before being engulfed by the
fish probably led to the better growth results
exhibited by the fish given the powdered food.
An
ultrastructural study of the development of
the dermal iridophores and structural pigmentation
in Poecilia reticulata (peters)
R. E. Gundersen, E. R. Rivera *
Department of Biological Sciences, University
of Lowell, Lowell, Massachusetts 01854
*Correspondence to E. R. Rivera,
Department of Biological Sciences, University
of Lowell, Lowell, MA 01843
Abstract
Three general stages of iridophore development
were found in Poecilia reticulata that correspond
to the development of structural pigmentation.
The first stage was prevalent in fish embryos
about to hatch to young fish 4 months old.
Dermal cells containing elements of endoplasmic
reticulum and a Golgi apparatus developed
into iridophores. The endoplasmic reticulum
early in iridophore development became a few
sparse cisternae, and the Golgi apparatus
elaborated long rectangular vacuoles with
two membranes. From 5 to 15 vacuoles were
arranged in parallel stacks in each developing
iridophore. Crystals of guanine were deposited
within the inner compartment of each vacuole.
At this stage of development, the young fish
had only a few dermal iridophores next to
the lateral muscle. Fish 4 to 6 months old
had a more advanced type of iridophore development
including several layers of iridophore cells
in the dermis. The innermost iridophores near
the muscle had many mature crystal-containing
vacuoles (iridosomes). Each cell had upt to
three stacks of 10-20 iridosomes with their
long axis oriented at a slight oblique angle
to the surface of the fish. The outer layers
of iridophores resembled the immature developing
cells found in very young fish. The third
developmental stage was found in sexually
functional adults. All dermal iridophores
contained 2-3 groups of 10-20 mature iridosomes.
In mature iridophores, the Golgi apparatus
was not found in the cytoplasm. The thickness
of the guanine crystals (70 nm) and cytoplasmic
intervals (90 nm) results in a constructive
interference reflection of 496 nm (blue-green).
This iridescence increased concomitantly with
the increase in iridophore cells in the dermis
and the maturation of their iridosomes.
Sex-specific effects
of carotenoid intake on the immunological
response to allografts in guppies (Poecilia
reticulata).
Proc Biol Sci. 2004 Jan 7;271(1534):45-9.
Grether GF, Kasahara S, Kolluru
GR, Cooper EL.
Department of Organismic Biology,
Ecology and Evolution, University of California,
621 Charles E. Young Drive South, Los Angeles,
CA 90095-1606, USA. ggrether@ucla.edu
Rarely are the evolutionary
origins of mate preferences known, but, recently,
the preference of female guppies (Poecilia
reticulata) for males with carotenoid-based
sexual coloration has been linked to a sensory
bias that may have originally evolved for
detecting carotenoid-rich fruits. If carotenoids
enhance the immune systems of these fishes,
as has been suggested for other species, this
could explain the origin of the attraction
to orange fruits as well as the maintenance
of the female preference for orange males.
We used the classic immunological technique
of tissue grafting to assay a component of
the immune response of guppies raised on two
different dietary levels of carotenoids. Individual
scales were transplanted between pairs of
unrelated fishes, creating reciprocal allografts.
Transplanted scales were scored on a six-point
rejection scale every day for 10 days. Five
days later, the same pairs of fishes received
a second set of allografts and were scored
again. Compared with low-carotenoid-diet males,
high-carotenoid-diet males mounted a significantly
stronger rejection response to the second
allograft but not to the first allograft.
High-carotenoid-diet females, however, showed
no improvement in graft rejection compared
with low-carotenoid-diet females. To our knowledge,
this is the first experimental evidence for
sex-specific effects of carotenoid consumption
on the immune system of a species with carotenoid-based
sexual coloration. These results are consistent
with the hypothesis that the mate preference
for carotenoid coloration is maintained by
the benefits to females of choosing healthy
mates, but they cast doubt on the idea that
the benefits of carotenoid consumption, per
se, could account for the origin of the preference.
The sex-specificity of carotenoid effects
on allograft rejection in guppies provides
indirect support for the general hypothesis
that males pay an immunological cost for sexual
ornamentation.
Sexual responsiveness
is condition-dependent in female guppies,
but preference functions are not.
BMC Ecol. 2004 Apr 29;4(1):5.
Syriatowicz A, Brooks R.
School of Biological, Earth
and Environmental Sciences, The University
of New South, Wales, Sydney 2052, N,S,W, Australia.
allie@squiz.net
BACKGROUND: Variation in mate
choice behaviour among females within a population
may influence the strength and form of sexual
selection, yet the basis for any such variation
is still poorly understood. Condition-dependence
may be an important source of variation in
female sexual responsiveness and in the preference
functions for male display traits that she
expresses when choosing. We manipulated food
intake of female guppies (Poecilia reticulata),
and examined the effect on several measures
of condition and various components of mate
choice behaviour. RESULTS: Diet significantly
influenced four measures of female condition:
standard length, weight, reproductive status
and somatic fat reserves. Diet also significantly
affected female sexual responsiveness, but
not preference functions: females in good
and poor condition prefer the same males.
CONCLUSIONS: Variation in female condition
within populations is therefore unlikely to
influence the direction of sexual selection
imposed by female choice. It may, however,
influence the strength of sexual selection
due to its effects on female responsiveness.
The relative importance of female choice as
a sexually selective force may also covary
with female condition, however, because low
responsiveness may result in sneak copulations
being relatively more important as a determinant
of the paternity of offspring. Differences
among populations in mean condition may also
influence geographic differences in the strength
of sexual selection.
Marginal differentiation
between the sexual and general carotenoid
pigmentation of guppies (Poecilia reticulata)
and a possible visual explanation.
Physiol Biochem Zool. 2003 Nov-Dec;76(6):776-90.
Hudon J, Grether GF, Millie
DF.
Provincial Museum of Alberta,
12845 102 Avenue, Edmonton, Alberta T5N 0M6,
Canada. jocelyn.hudon@gov.ab.ca
We present the first detailed
analysis of carotenoid pigmentation of the
integument of guppies (Poecilia reticulata
Peters), quantifying variation in carotenoid
content and composition of wild guppies from
three drainages on Trinidad (1) between the
sexual and general pigmentation of males,
(2) between the sexes, and (3) geographically
in relation to carotenoid availability. We
report that the carotenoid pigments in the
integument of guppies are predominantly esters
of tunaxanthin. The peak wavelength of carotenoids
in the orange spots of males lay only ca.
2.8 nm higher than that of pigments outside
of the orange spots, and the peak wavelength
of carotenoids in the male whole integument
does not differ from that in the female whole
integument. Carotenoid composition of the
general integument of females and the non-orange
spot fraction of males, but not of the orange
spot fraction of males, varied with diet,
correlating with the ratio beta-carotene to
lutein in the different streams. Male guppies
deposit higher concentrations of carotenoids
in their orange spots than in the rest of
the integument (five to nine times higher),
but not at the expense of the general integument,
which was similarly endowed as the general
integument of females, even in carotenoid-poor
streams. Presumably males absorb/retain more
pigments than females. Photoreceptor-based
simulations suggest that tunaxanthin provides
both greater brightness and chroma than would
4-keto-carotenoids such as astaxanthin.
Possible role of female
discrimination against 'redundant' males in
the evolution of colour pattern polymorphism
in guppies.
Proc Biol Sci. 2004 Aug 7;271
Suppl 5:S299-301.
Eakley AL, Houde AE.
Department of Biology, Lake
Forest College, Lake Forest, IL 60045, USA.
Multiple paternity of offspring
can result from active preferences on the
part of females or sexual harassment by males.
We examined sexual responses of female guppies
to a previous mate versus a novel male (experiment
1) or to a male with a colour pattern similar
to that of the previous mate versus a novel
male (experiment 2). Females showed significantly
more sexual responses to courtship by novel
males than to previous mates in experiment
1 or to males that resembled previous mates
in experiment 2. These results suggest that
females discriminate actively against previous
mates, and extend this discrimination to males
with similar colour patterns to previous mates.
This could lead to negative frequency-dependent
sexual selection against common colour patterns
(a 'redundant male effect'), which could contribute
to the maintenance of the extraordinarily
high levels of genetic polymorphism in guppy
colour patterns.
