Use of
Methyltestosterone for Masculinization of Xiphophorus hellerii
Swordtail production is important to
Florida aquaculture but is under economic
pressure from imports. Male swordtails possess
an extended lower spike (i.e., sword) on the
tail, which is the desired phenotypic
characteristic for the ornamental trade of this
species. Females, which usually make up greater
than half of the production of this species,
lack the sword and consequently are far less
valuable than males. An increase in the
proportion of fish with swords will boost
average price per fish and enhance producer
economics. Masculinization results in sword
development in females and increases the
farm-gate value of these fish. This is a USDA/CSREES-funded
project working with the Food and Drug
Administration on an Investigational New Animal
Drug (INAD) application for methyltestosterone
as a masculinization agent for swordtail, Xiphophorus hellerii, an important
ornamental species. Results of tank
studies support labeling by producing 100%
masculinization of formerly phenotypic females
under all treatment protocols, but work remains
to demonstrate environmental safety and pond
treatment efficacy. Preliminary pond studies
showed high rates of masculinization (84-88%).
A protocol for pivotal effectiveness
studies has been approved by the Food and Drug
Administration (FDA) and trials should begin in
Fall 2006. This research also will
serve as a foundation for Investigational New
Animal Drug (INAD) label extensions involving
other tropical ornamental fish with high value
phenotypic males and low value phenotypic
females.
Design Criteria
for Recirculating Ornamental Fish Production
Systems
The use of recirculating system technology
is expanding in commercial aquaculture, but
initial system and operation costs can reduce or
eliminate profitability. Ornamental
species can be divided into major groups based
on water quality, nutrition, and trophic-level
parameters. Categorizing species into groups
and testing these groups with model production
systems will help fine-tune design criteria and
system applications and thereby enhance the
economics of these low water discharge systems.
This is a USDA/CSREES-funded project developing
design criteria for various ornamental species,
using swordtails, Xiphophorus hellerii,
as the initial study animal. A pilot scale
system was built and a one year study of growth,
survival, and economics was conducted.
Improvement of
Harvesting, Grading, and Transportation
Technologies for Ornamental Finfish
Harvesting, grading, and transportation are
critical and labor-intensive stages in tropical
ornamental aquaculture. These are often the
stages when fish stress and mortality are
highest, so improvements during these stages can
lead to vast improvements in product quality and
quantity, and therefore production
profitability. This is a USDA/Southern
Regional Aquaculture Center (SRAC)-funded
project which investigated current practices and
new technologies, and extended results for this
key portion of ornamental production.
Experimental trials were conducted comparing
common industry practices and alternative
practices for each stage in the process of
harvesting, grading, and transporting tropical
aquarium fish from the production pond to the
wholesaler. In some cases, one or more current
practices proved superior to alternatives. In
other cases, alternative technologies were
developed (e.g., new cage type for collecting
larger tropical ornamental fish). Most
improvements were incremental, but some common
existing practices were found to be far less
effective than others. Four University of
Florida Cooperative Extension Service EDIS
publications are in final revision.
Water Quality
Analysis of Ground and Surface Water Discharge
from Commercial Ornamental Fish Farms in Florida
Florida has implemented BMPs for aquaculture
that seek to streamline regulations while
simultaneously protect the environment. A major
part of the BMPs covers farm discharge and its
potential effects on ground and surface waters
of the state. This is a USDA/CSREES- and FDACS-funded
project which analyzed one year of data from
monthly samples taken from five tropical fish
farms in the state, concentrating on total
nitrogen, total phosphorus, and total suspended
solids to test the efficacy of Aquaculture Best
Management Practices (BMPs) implemented by the
Florida Department of Agriculture and Consumer
Services. Results support the efficacy of state
BMPs for tropical fish producers.
Special Local
Need Label for Dylox 80
Because of large the expense of re-labeling
and small markets, many common aquaculture
pesticides have been lost when their aquatic
labels expired. This project used the Section
24(c) registration program to bring a useful
chemical tool back into the tool kits of Florida
ornamental fish and aquatic plant producers.
This project resulted in the obtainment of a
Special Local Need (SLN) label for Dylox 80
for use in ornamental fish and plant production
systems on farms holding a Florida Department of
Agriculture and Consumer Services aquaculture
certificate. Dylox 80 is a pesticide commonly
used in the past in aquaculture but its aquatic
labeling had expired. The new EPA labeling
allows the use of Dylox 80 for the control of
predaceous zooplankton and amphipods in
commercially operated freshwater systems used
only for ornamental fish production and non-food
aquatic plant production.
Development of
Design Criteria for Greenhouse Production of
Marine Ornamentals
Marine ornamental production has economic
potential if low-cost, inland greenhouse systems
can be employed. This is a USDA/CSREES-funded
project developing design criteria for inland,
greenhouse-based production of marine ornamental
species, using giant clams, Tridacna crocea,
as a model species. System design criteria
include lighting requirements for photosynthetic
symbionts, filtration requirements, temperature
control, and water use. Prototype design
criteria will be developed for economic,
commercial production techniques for marine
ornamental species. Experimental treatments
tested the effects of recirculating (i.e.,
complex filtration consisting of low discharge
bead filter, UV sterilizer, protein skimmer, and
chiller) and roll-over (i.e., simple filtration
consisting of live rock and blower-driven
airlifts) systems with three different light
regimes (shade cloth, no shade, or metal halide
lighting) on growth, survival, and color of seed
clams. Although survival was relatively low in
all treatments, results indicate that shade
cloth or no shade was superior to metal halide
and that the recirculating system was superior
to the roll-over system.
Coral Propagation
and Restoration
There is a substantial need for hard coral
fragments for restoration efforts. If
aquacultured corals are successful and health
certification procedures can be developed,
Florida aquaculture could provide fragments for
restoration and potentially establish a captive
source of these CITES-listed corals for sale in
the commercial marine aquarium industry.
This is a USDA/CSREES-funded project to compare
growth and survival of native hard coral
fragments in three types of production systems
(land-based indoor high-end recirculating
system, land-based greenhouse recirculating
system, and ocean-based live-rock lease site)
with the eventual goal of providing coral
fragments for coral restoration projects (e.g.,
following ship groundings, construction, or
disease outbreaks). Nine species of corals
removed from disturbed sites in the Florida Keys
National Marine Sanctuary were fragmented and
distributed to the three experimental sites
where they will to be monitored for survival and
growth for one year. An acceptable procedure
and protocol for the issuance of a USDA-APHIS
certificate of health will be established to
allow the safe return of cultured corals into
open waters. The protocol is currently in
development, in collaboration with colleagues
from the Florida Keys National Marine Sanctuary
(NOAA) and the Florida Fish and Wildlife
Conservation Commission. After one year and
pending certification of health, coral fragments
from all three experimental sites will be
introduced onto a restoration site in the
Florida Keys and monitored for health and
survival.
Use of Stable
Isotopes to Evaluate Feed Quality and
Characterize Aquaculture Pond Trophic Dynamics
to Maximize Fish Production
There is much variation in current
practices of feeding and fertilizing
ornamental and bait fish production ponds.
Additionally, there is considerable
variation in production from pond-to-pond,
even on a single farm. This is a USDA/CSREES-funded project attempting to answer
a basic question of pond-based aquaculture
regarding the fate of nutrients from commercial
fish feeds in a pond—do small fish primarily
obtain their nutrition from relatively expensive
commercial feeds, from live organisms (best
supported by relatively cheap fertilizers), or a
combination of both? This study will track stable isotopes of
carbon and nitrogen through pond and
experimental food webs to determine nutrient
fate. This will be coupled with traditional
production studies using replicated ponds with
the application of one of four
treatments—nutritionally complete commercial
feed, un-processed meal commercial pond feed,
organic fertilizer, or inorganic fertilizer.
Tank studies will be used to test assumptions of
the isotope tracing methodology concerning
protein and carbohydrate assimilation as a proxy
for feed quality when compared to traditional
grow-out trials of the feeds. Results of 90-day
indoor tank trials investigating growth of
swordtails, Xiphophorus hellerii, fed
five diets varying in protein source ranging
from 100% of protein from fish meal to 100% of
protein from wheat meal show decreased growth in
the 100% wheat meal treatment relative to the
others. These feeds are being evaluated for
ammonium production and ammonium isotope
signatures. Additionally, this
project will test a novel method of
pre-screening fish feeds that could reduce the
costs of feed development.
Feed Formulation
and Feeding Strategies for Bait and Ornamental
Fish
Ornamental fish producers currently use
a variety of fertilizing and feeding
strategies based largely on personal
experience. This is a USDA/SRAC-funded project comparing the total
production, growth, survival, and economics of
ornamental fish in ponds under various
fertilizing or feeding regimes. Six representative species will be
tested in replicated ponds using four
treatments—organic fertilizer, inorganic
fertilizer, meal-based, minimally-processed
commercial pond feed, and the latter feed after
processing, pelletizing, and re-grinding.
Additionally, each species will be tested in
tank grow-out trials using the same feeds. The
12-week grow-out cycle for the first species,
zebra danio, Danio rerio, was recently
completed and preliminary results indicate that
fed ponds produced more fish (numbers and
weight) but that ponds fertilized weekly with
organic fertilizer had a higher
return/investment ratio for the costs of any
input treatment tested. Given the differing fertilizing and feeding
practices in pond-based ornamental aquaculture
and the wide variety of species cultured,
evaluation of these practices using
representative species will provide the industry
with important information that could reduce
costs and increase production.
Use of Chemical
Antibacterial Agents in Tropical Ornamental Fish
Shipping Bags Bacterial loads can
increase in shipping bags during transport and
potentially compromise the health of transported
fishes. Although a number of chemicals are
commonly used by producers, these have not been
tested for efficacy. This is a Florida Tropical
Fish Farms Association (FTFFA)-funded project
examining the efficacy of common shipping
additives on reducing the bacterial loads in
ornamental fish shipping bags. Producers use a
number of chemical treatments in shipping water
to reduce bacteria, but these additives have not
been tested for efficacy. Experiments to date
have been conducted with several commonly used
chemicals in bags with fish (swordtail, Xiphophorus helleri). Experiments will be
conducted on bags lacking fish but inoculated
with bacteria (Aeromonas hydrophila, a
common opportunistic bacterial pathogen of
fish).
Use of Sedatives
to Reduce Handling Stress in Three Spot Gourami
Trichogaster trichopterus
Stress can be an important precursor to disease
and mortality in cultured fishes. Levels of the
hormone cortisol are often used to detect stress
in fish. The discovery of anesthetics that are
useful not only for sedation but also for
stress-reduction can reduce mortality during
handling and shipping and ultimately increase
product quality and producer profitability. This
project tested the efficacy of anesthetics for
sedation of Three Spot Gourami, Trichogaster
trichopterus, an important ornamental fish,
as measured by behavior and the efficacy of
several commonly-used shipping chemicals,
including anesthetics, in reducing blood plasma
cortisol levels. Results suggest that some
anesthetics are effective at reducing stress
hormone levels in Three Spot Gourami.
Examination of
Immune System Development in Juvenile Redtail
Black Sharks
The redtail black shark and other similar
species are important tropical ornamental
species but are susceptible to high mortality
from outbreaks of Streptococcus iniae.
Providing protection from this pathogen via
vaccination will result in fewer losses of
valuable brood fish during spawning and
production fish during harvesting and holding.
This is a USDA/CSREES-funded project
investigating feasibility of techniques for
examining the ontogenesis of the immune system
in an economically important ornamental fish,
the redtail black shark Epalzeorhynchus
bicolor. This project complemented earlier
research on vaccination of this species for a
common bacterial pathogen, Streptococcus
iniae. A description of the immune system
development is an important step in determining
when to apply vaccines. Work accomplished to
date examined potential for use of biological
products from the taxonomically related
cyprinid, Cyprinus carpio for use in
antibody quantification in plasma. Although
there is some cross-reactivity with redtail
black shark antibodies, this cross-reactivity is
not strong. Immunohistological and molecular
techniques are currently in progress using other
related species reagents (such as the zebra
danio, Danio rerio).
Pyceze ® Research
Study
There is a
recognized need in the ornamental aquaculture
industry for more efficacious anti-fungal
compounds. Currently available compounds have
limited efficacy. This was a Novartis
Animal Vaccines Limited-funded study of the
potential toxicity and water stability of Pyceze®,
an anti-fungal therapeutant.
Pyceze® has
demonstrated great potential internationally in
food fish species as a tool against
Saprolegniasis (a common fungal disease causing
heavy economic losses) and in preliminary trials
with ornamental fish.
Experimental manipulations demonstrated
no observable toxicity to three common tropical
ornamental fishes (neon tetra, Paracheirodon
innesi, platy, Xiphophorus maculatus,
and common pleco, Hypostomus sp.). The
water stability of Pyceze ® increased with
decreasing hardness and pH.
Aquaculture
Investigational New Animal Drug (INAD) Research
Few aquaculture drugs or chemicals are
currently approved and this is a major
impediment to the growth and competitive
ability of US aquaculture. Ornamental fish are
transported worldwide. This is USDA/CSREES-funded project providing drug
effectiveness and target animal safety data to
the Food and Drug Administration (FDA) through
the INAD process in support of New Animal Drug
Approval (NADA) for metomidate hydrochloride (Aquacalm),
florfenicol, and emamectin benzoate (SLICE) for
ornamental fishes. Metomidate has promise
as a safe and effective sedative to reduce
mortality and improve condition of ornamental
fish during transport. Few antibiotic
treatments are available for bacterial
infections and florfenicol would provide a
potentially powerful and effective antibiotic
feed-additive. SLICE has been a safe and
effective agent against crustacean parasites in
salmon culture and could be an important
therapeutant for ornamental fish with similar
external parasites. Protocols for pivotal
effectiveness studies are being developed for
review and approval by FDA under an INAD for
metomidate. Initiation of INADs for florfenicol
and SLICE will be pursued. Data from this study will provide
FDA with information necessary for approval of
these three products.
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