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Current and Recent Research Projects

Ornamental Aquaculture Production and Management v Aquatic Animal Health v Ornamental Fish Reproduction v Nonindigenous Aquatic Species Ecology and Management

Ornamental Aquaculture Production and Management

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. 

Aquatic Animal Health

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.

Ornamental Fish Reproduction

Topical and Immersion Application of GnRHa to Selected Characins
Hormone injection is a common method for inducing spawning in aquaculture.  Nevertheless, this method can result in disease outbreaks or mortality due to stress.  Alternative, less stressful induction methods could result in better broodstock management.  This is a USDA/CSREES-funded project investigating alternatives to injection application of gonadotropin-releasing hormone (GnRHa), an important spawning aid for fishes, to a species of characin (bleeding heart tetra, Hyphessobrycon erythrostigma) with economic importance.  Experimental regimes included bath treatments at various concentrations and gill applications.  All procedures proved ineffective for the target species; however, gill application of reproductive hormones dissolved in dimethyl sulfoxoide (DMSO) resulted in ovulation in another model species, a cyprinid, the rainbow shark, Epalzeorhynchos erythrurus

Nonindigenous Aquatic Species Ecology and Management

Diet of Asian Swamp Eels Found in Commercial, Tropical Fish Production Ponds
Predator control is a major management concern in tropical ornamental aquaculture.  Much of the ornamental fish production in Florida is conducted in small ponds containing high densities of vulnerable, yet valuable fishes.  The Asian swamp eel has appeared as an introduced species in commercial tropical fish production ponds in Hillsborough County, a center of aquaculture production in Florida.  Based on initial information from federal agencies, great concern was expressed regarding the impact of this exotic predator on fish populations in production ponds.  This is a USDA/CSREES-funded project collecting Asian swamp eels, Monopterus albus, from tropical fish production ponds and examining their stomach contents.  Results of stomach contents examinations indicate that Asian swamp eels in ornamental aquaculture ponds are not a significant threat to fish production.  Other common food items included aquatic insects, worms, and crustaceans.  Information from this study is assisting producers in gauging the relative threat posed by Asian swamp eels and provides information for management recommendations.  Recommendations include management of vegetation and sediment loads in ponds, thorough washing and preparation of ponds between production cycles, and attention to predator control and biosecurity.  However, aggressive eradication is unwarranted.

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Last updated October 02, 2012.
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