Spawning and Production of the Lemon Tetra Hyphessobryconpalchripinnis
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HAWAU-T-99-002 C2 LOAr c Spawning and Production of the Lemon Tetra Hyphessobryconpalchripinnis Brian Cole, M.S., Paul Kotal, M.S. and Michael Haring, B.S. Sea Grant Extension Service School of Ocean and Earth Science and Technology February 1999 Center for Tropical and Subtropical Aquaculture Publication Number 142 ACKNOWLEDGMENTS The authorswish to extenda sincerethank you to all who contributedto the completionof this manual,including Alcian Clegg and Jean McAuliffe of theCenter for Tropicaland Subtropical Aquaculturefor layoutand editing, and Diane Nakashima of theUniversity of HawaiiSea Grant CommunicationsOffice for printingadvice and assistance. The production of this fact sheetis the combined effort of three institutions. 1! TheUnited States Department of AgricultureCenter for Tropicaland Subtropical Aquaculture CTSA!through a grant&am the U.S. Department of Ayiculture Cooperative State Research, Educationand ExtensionService USDA grants¹96-38500-2743 and ¹97-38500-4042!. 2! TheUniversity of HawaiiSea Grant Extension Service SGES! through the National Oceanic and AtmosphericAdministration NOAA!, project ¹ A/AS-1,which is sponsoredby theUniversity of HawaiiSea Grant College Program, School of OceanEarth Science and Technology SOEST!, underInstitutional Grant No.NA86RG0041 &om NOAA Office of SeaGrant, Department of Commerce, UNIHI-SEAG1VLNT-TR-99-04. 3! TheAquaculture Development Program, Department of Agriculture, State of Hawaii,as part of theAquaculture Extension Project with theUniversity of HawaiiSea Grant Extension Contract ¹ 44576. Theviews expressed herein are those of theauthors and do not necessarilyreflect the views of the funding agenciesor their sub-agencies. SEA GRANT Table of Contents INTRODUCTION TAXONOMY MORPHOLOGY . DISTRIBUTION . WATER QUALITY REPRODUCTIVE BIOLOGY . GROWTH LITERATURE CITED. INTRODUCTIO'N Whilemore than 60 speciesin thegenus Hyphessobrycoii have bccn identified, very few areavai l ableon theornamental market despite their popularity Baensch1993!,Hyphessobrycov pu chripi nnis Lemon tetra!is just oneof manyfish in thegroup of tetrasor moreaccurately, Characins, traded in theornamental industry.Lemon tetras are peaceful and nonaggressive to other fish anddo well incommunitytanks. Like manyof theother tetras, they can be considered a schoolingfish anddo betterin groupsof five to twenty individuals. AlthoughLemon tetras are fairly easyto spawn,they are not as colorful as many of thc othertctras and are not widely spawnedor importedin largequantitics for economicreasons Axelrod and Schultz 1983!. As of 1992,the Lemontetra was listed as number 69 in the]ist af top 100fish importedinto theUnited States with just over5,300 imparted per month Chapmanet al. 1997!.Thc historical estimated farm gateprices producerscould expect for a groupof variousone-inch Hyphexvobrycon sp. are summarized in Figurc 1. Theseprices were taken from a seriesof priceJists published every five yearsby oneAsian trans-shipper. A one-inchfish wasused to serveas an easy reference point, although many can be sold at smallersizes. The Lemon tetra could be consideredwhat the industry refers to as a "breadand butter" item. Estimated Farm Gate Prices 0.18 0.16 0.14 0 0.12 8 0.1 Co 0.08 D 0.06 0.04 0.021980 1985 1990 1995 Year Figure l. Estimated average farm gale prices for selcctcdone-inch Hyphessohryconsp. TAXONOMY TheLemon tctras, un1ike many tropical fish traded onthe ornamental market, have not gone through reclassifieationsandnumerous name changes ashave others, This fish was occasionally called Hemigrammus ervthrophthalni usbut is not valid scientifically Axelrod etal. 1977!. J.Gery discovered thatthe generic name for the more common species was possibly incorrect but since it was in such common usagehedid not assign a new one and suggested thata reviewofall South American Tetragonopteri nae beundertaken, Todate this review has not occurred. TheGenus Hyphessobrycon wasestablished in 1908 byDurbin Baensch 1993!. Todate, thctaxonomic classification remains; Family: Characi dae,Subfamily: Tetragonopterinae,Genus: Dyphessobrycon, Species: pulchripinnis, MORPHOLOGY Hyphessobryconpulchripi nnis are not as colorful as many of the other Characins unless well maintained andgiven feeds with the proper level ofavailable carotenoids toenhance andmaintain theircolor. They do makeanexcellent contrast fishdue to the bright yellow color and the bright red upper part of the eye. As showninFigure 3,mature adults are fairly easy toscx. The females have a deeperbodycontour andthe blackedge ofthe anal fin inthe males ismore pronounced thanin the females. Fully grown Lemon tetras arefrom three tofive centimeters cm!in length with a fivecm speciinen beingunusually large. Figurc3. Photographof Hyphessobry conpulchripinnis male top! andfemale bottom!. DISTRIBUTION Distributionis throughout South America Figure 2! exceptthe southern part and arid Pacific slope of Chile Axelrodand Schultz 1983!. The native habitat comprises the small tributaries of thelower Amazon basin, primarilybrooks emptying into the Rio Curua do Sol and the lower and rniddle Rio Tapajoz between Itaitubaand Jacare Acanga Gery 1980!, Figure2. Naturaldistribution of Hyphessobrycon pulchripinnis. Modified from Baensch1991!, WATER QIJALlTY Properwater quality is oneof themost important aspects for successin spawningCharacidae. Most prefer softand acidic waters. Table 1 providesthe ranges in waterchemistry considered acceptable for theproduc- tion of Hypjiessobryconpulchripiniiis, Table1 .Ranges in importantwater quality parameters for thereproduction of Lemontetras. Waterchemistry can vary greatly in Hawaiidue to thewide range of environmentaland geological condi- tions encounteredthere. While water sourcesthat fit within theseparameters can be found in the State,in somecases, the water chemistry may have to bealtered to successfullybreed some fish. For many tetras, hardnessand pH are the inost important parametersto consider.Hardness is the total concentrationof alkalineearth ions expressed asan equivalent calcium carbonate CaCO,! in mi1 ligramsper liter mg/L!, with theprincipal components being calcium and magnesium carbonate or sulfate.Hard water contains high concentrations of alkaline earth ions while soA water has low concentrations. Other ions contribute to hardnessbut are usually present in suchminute quantities that their effect is minimal.Hardness is usually expressedas temporary or carbonatehardness and permanentor non-carbonatehardness. The sum of thesetwo components istotal hardness and is usually expressed asmg/L CaCO, Boyd 1979!. The term "temporaryhardness" is commonlyused because carbonate hardness can be removed by precipitatingthe calcium andmagnesium cations or saltsby boiling. The most common method to reduce hardness is to dilute the hard water with distilled water. Other means includeuse of a cornrnercialwater softener such as reverse osmosis units or ion exchangegel filters if large quantitiesof soA water are needed, ThepH is a measurementof a water'sacidicity and indicates a changefrom a neutralpH of 7,0,Neutral watercontains an equal balance of hydrogenions and hydroxide ions. A higherproportion of hydrogenions resultsin a moreacidic water lowerpH! while a higherproportion ofhydroxide ions results in a more alkalinewater higher pH!. I fsmall quantities of waterare needed, reduction of pH is generallya simple matterand can be achieved through peat filtration. If largequantities of waterare needed, a stronginorganic acidsuck as phosphoric, sul furic, or dilutedhydrochloric muriatic! can be used to reducepH. Thereare alsocommercially available compounds sold through retail pet stores in theform of solidtablets, granules or liquid drops. When using a strongacid to reducethe p H,be sureto run severaltests to determinehow much acid is requiredto reducethe pH of a givenamount of waterto thedesired level. When handling strong acids, reviewand observe all safetyprecautions to preventaccidental spills or exposureto eyesand skin. REPRODUCTIVE BIOLOGY Many speciesof fish produceeggs only oncea yearwhile someothers produce eggs repeatedly over thecourse of a spawningseason. Lemon tetras fall into thelatter category. Female Lemon tetras will ovulate on averageabout once every four days as shown in Figure 4 Burt et al,1988, Nakatsuru and Krarner 1982!.During each ovulation, a femalewill spawnan average of 23 timesproducing an average total of 160 eggs.Ovulated eggs are sinking and slightly adhesivewith diametersof 0.74 mm that swell to 0.90 mrn aAer waterhardening. Spawning is promiscuousand males will spawnevery day that receptive females are available Nakatsuruand Kramer 1982!. Fertile eggs hatch in about24 hoursand there is no parentalcare given to the eggsor fry. Thismay lead many aquacuIturists tobelieve that there may be an unlimited ability for males to fertilize eggs. However,Nakatsuru and Kramer found that there may indeed be a limitationto themales' ability to fertilize eggs.The percentage of developing eggs declines as a functionof thenumber of spawningacts by themale. Thedecline is most easily explained by a reductionin the quantity or quality of spermreleased atsuccessive spawnings Nakatsuru and Kramer 1982!. Ovulation Intervals 30 25 20 I5 I 0 I 2 34 5 6 78 910 I l Interval Length in Days Figure4. Percentdistribution of'ovulations since previous ovulation for Hyphessobrycon pulchripinnisunder controlled conditions n=245!. Modifiedfrom A. Burt. 1988! Therate of externalfertilization is maximizedonly at sperinconcentrations of 1,000,000sperm per milliliter