Raising Fresh Fish in Your Home Waters养鱼技术.docx

RaisingFreshFishinYOUrHomeWaters养鱼S#AprojectofVolunteersinAsiaby:BrendaBorta,JackRuttle1andMarcPodemsewspInc.33Ea8tMinorStreetEmmaws,BA18049USAbo,Inc.BrendaBortzJackRuttleMurcPodsmsWIWBEAF1SHFARMERStManypeoplethinkoftishasapotentialcrop.Ru:thatsjustwhatcarp,catfish,trout,andbassare.Tillrecently,fi3hhasbeenawiIdfoc:dinthiscountry-huntedandcaddhtinopctnwater:,thentakenhomeortomat.Butallthatischanging.Wildstockisbeingdcletrdbyoverfishingandcou!;"mirlatcclbyindustry,andthecostottrcshandfrozenfishkeepsclinbing.21.uckily,theresahappyendingtothisfishstory.Inotherlandspeoplehavebeenstocking,breeding,feed-ing,andharvestingfishforcenturies.Andmorerecently,Americansin-tistshavebeguntodomesticatede,siratlenativespeciesliketruutandr%,tfish.Puttingthisknowhowtowork,CUmmer1.iaIfarmsnowraisehugenumbersoffishmuchlikeagribusi-nesserodeextieandchickens.Attheoth,.extreme,countrypeopiestillen,Olthefarmpond-stockedfor;ecre,Itionandoccasionalmeals,butnottrulycultured.Now,though,theresamiddleground.Itsabackyardfishculture,;Imethodthatletsyougrowfish1ikeagardencrop.1.ikethefoodsyougrowin4,Ihcfishinyourwatergardenwillneedregularattentionandfeedingorfertilization.Caredforinthisway,apondthesizeofamodestswimmingpoolcansupplyenoughfishforafamily,Artdatypicalfarmpondcanyieldenoughtohaveplentyleftoverforsale.Backymlfishvs.barnyardanimaleFormanypeople,acropoffishcanalsoturnouttobethebestchoiceinlivestock.Highlydigestibleandlow,infat,fisharerichinprotein.Andtheirproteincomesclosert.meetingthebodysneedsthanmeatproteindoes.Sincefisharecoldblooded,theydontburnfoodjusttokeepwarm.WhichmeanstIicyarconeoftIitsmostenergyefficientlivestockaround.Andunlikebarnyardanimals,theyreabsolutelyquidandodorless.Sincetheresnopenormanurepiletooffendtheneighbors,raisingfishis.analmostinvisiblewilytogrowSonirofyourownnitintownorinthesuburbs.GREATINGAB1.ANCEDJtlikeorganicgardening,fishculturrinvolvesworkingwithawholelivingsystem.Ihcwaterthatwillbeyourgrowthmediumismuchmorethantheequivalentofnourishinggardensoil.Itsalsotheatmospherethatprovideslife-givingoxygen.Manyforcesinteractinthistotalen-vironmtnt,andasabeginnerinaquacultureyou11wanttoknowaboutthosethatdirectlyaffectfish.Cleanwaterisamustinfishcul-ture,andfortunatelythewaterinmostfarmponds,ruralstreams,springs,andwellsisnaturalIyclean,Keepinmind,though,thatthekindofwaterbestforfishfarmingisfarfromcrystalclear.healthybloomofalgaeisvitaltoahigh-yieldingsys-tcm,andthesemicroscopicpeagreentoruddybrownplantscanmakewaterlooksoupy.Ifyoususpect,however,thatyourwatersourcecontainsman-madepol-Iutants,youshouldhaveitanalyzed.YourcountyAgriculturalExtensionAgentoryourstatesFishandCameCommissionpeoplecantellyouhowtodothis.Youmustalsobealerttonaturalsourcesoftrouble.Evenordinarysoi1aidec!byerosionortherootingofduckscanfoulwatertoonluchforthefishesliking,Inheavi1ystockedlx)ndg,droppingsfrmthefishthem-selvescangetthickenought,tnclog110withtinyparticles.Uncon-SUmCdbitsoffoodcandothesamething.Happily,theseprrblemsarent72*common-especiallywhenotheror-g;Inismsinthepondaredoingtheirwork.Temperatureiscrucial.Becausefisharecoldbloodedanimals,theycanbegrownonlywhenandwheretheclimateandwatersupplycooperatetoprovidewatertemperatureswithintheirgrowingrange.Moreover,eachkindoffishfavorsaspecificitimperatureringe.Someflourishonlyincoldwaters.OtherswontgrowandreproduceWellunlessthewaterisverywarm.Thewatertemperatureyouwillhavetoworkwithcanbecloselytiedtothetemperatureofyourwatersource,Ifym-sourcewaterflowsfastfromanundergroundsupply,itstemperaturewillberough1ythesameasthatofthegroundwaterinyourarea.(SeeFig.1,)Ontheotherhand,ifyourscrurctwatertricvklcsfrombe1owemendratherthangushes,itwillbewarmedsomewhatasitpassesslowlythroughthegroundbelowthefrostline.irtemperaturealsogreatlyinflu-encespondwatertemperatures.saruleofthumb,watertemperatureinapondtendstnapproachtheaver-ageairtemperature.Ibgetagoodideaofwhatthatis,scanthetableofaveragemonthlytemperaturesforyourarea.(GetthisfromthenearestU.S.WeatherBureau.Or1ookitupatthelibraryinTheClimdictlasqfthiUStsorinagoodalmanacorencyclopedia.1Sincepondwaterrespondsslowlytochangesinairtemperature,thewatertemperatureinyourpondwillbeslightlybehindthetemperatureriseinspringandthedropinfall.Forthesamereason,pondwaterisusu-allycoolerthanthehottestairduringthedayandwarmerthanthecoolestairatnight.Thedeeperthepond,thelessthechangeinwatertemperaturebe-tweennightandday.Insmal1ponds,however,watcrtemperaturecanchangeafairamountonasummersdayandwillfollowseasonalchangesinairtemperaturemoreclosely,Thismeansthattobeonthesafesideinchoosingfish,youshouldknowbothaveragemonthlyairtemperaturesandtheapproximatehighesttemper-atureyourpondwaterisapttoreachinthesummer,(FishCommissionpeoplecanhelpyouwiththatesti-mate.)sallthissuggests,eachregionhasagrowing?ieasonforfish,Thoughpondsize,source-watertemperature,andclimateaffectthelengthofthisBeason,itwillcorres-pondrough1ytothefrost-freeperiodrdeninginyourarea,Hocloseitcomesyou11havetodeterminefromepg.Sence1mantinwinter,a1gaewillgrowa1it-tie.Watertcmpcrturt'willcentt_01therateoftrllactivityatanytimr.Averyroughrultbisthatthesptaectof1ifeproct*sstlsinfishandalgatdou-blcstV.i+heach15Friseintt'mptra-turc.Oxygenisbitaltohighyit+lsinfishculture.Unlike:1ir,waterhasverylit-tieabilitytoholdoxygen.In5partsofair,1partisoxygen.Kr(i1IGl-1ionpartsofwater,only11)ICoxy-gen.Andsotheavailabilityofoxygenisoftenwhatputsalimitonhowmuch1ifeapondcansuppert.Someoftheoxygenusedupbypondlifeisrcplatt'ctfromtheair.Coolerwaterwillholdmoreoxygenthanwarmwater.Sowhenoxygenlevelsfallbelowthenormatagiventemperature,oxygenmoleculesmoveintospacesinthewaterfromtheairaboveit.At50Fwaterwillhold11.3ppm(partspermillion)ofoxygen.AT60*Fthesaturationpointis9.6ppm,at70F-9ppm,at80F_8ppm.andat900F-74ppm.Nowitsmucheasierforrelativelyshallowpondsof3to5feetindepthtomaintainthesefulloxygenlevelsnaturally.Thatsbecauseshallowpondshavealargesurfaceareacom-paredtovolume,soalargerportionofwaterisincontactwiththeair.Windalsocanhelpgreatly.First,bymakingripplesorwaves,itmag-nifiesthesurfaceareaofapond,Second,windsteadilybringsfreshairinto*ontactwiththewater,thussteppinguptherateofoxygenex-changefromrichtodepletedareas.(1.argerpondstakeadvantageofwindbest,becausetheygivemovingairmorechancetokickupwaveo.)irladditiontoair,anothersourcechargeswaterwithoxygen.Itstheprocessofphotosynthesis,Wheneveroxygeniousedupinihewaterbybacteriabreakingdownor-ga11icmatter-orbyhigherformaofanimalandplantlife-carbundioxide4isproduced,Thisabundantgas,togetherwithsunlightandwater,isusedbyplantstomaketheirfoodviaphotosynthesis.ndsoforeachmoleculeofcarbondioxideplantstakein,theyreturnamoleculeofoxygentothewater.Themostimportantplantscon-tributingoxygentowaterarealgae,andunderidealconditionsalgaeandstillormovingairwillkeep:Ipondsupplied,Buttheamountofoxygenacultivatedpondwillneeddependsonhowmuchfishyouplantogrowinit.TheoreticaNyatleast,yourgoalinfishfarmingoughttobefirst,tofindthoanwntoffishthattheoxygeninyourwatercansupport,andbeyondthat,tofindwaystomaketheagatbpopulationhealthiersoitcandonatemoreoxygen.Butallthisiseasiersaidthandone,formanyfactorsmakeitdifficulttot.outItOili1fixtbdam、'UnIofoxygc*t'fromZdgiIcB.IiiktlofthtsnlNlytypc*SmakesOXYK'ViitiIdifftbrtbntriltt*.li)o,itsitiipo'siblt'totcI;rotwhichspecieswillgthtintoyourpond,ortotc41howtoCreiltcthet.onttitionsthatdtGrablr*typcswi11like.Moreovt*r,forPOapparenreasontheClOlllitlill'tspecaic5inyourpondmaychange-SlOWljiISthC!SUiISOtlprogresst5.Anothervari;rM'isthevtb：Ither,fortherattbofp:Iotosynthesisde-pendsdirec11yonthesun,Typically,theoxygenI、WISinyourpondwiltchangeevenDniCICNday.Ijymid-morningthedjtjwillb1hi114litwork,andtherewillheplentyofoxy-gen,Byearlyafternoonthedissolvedoxygenwillbeatmaximumconcen-Iration.Yourpondshouldstaysatu-ratedwithoxygennearlytosunset.Whenthetemperaturesarerightatthosetimes,youcanbesurethefisharefeedingactivcr.*andgrowingwell,eventhoughyoucattseetheminthepeasoup-greenthrIter.Atsunset,naturaloxygenproduc-tionstops,butoxygenusebyallpondlifegoeson.Bythenextmorning,nlevelswillbelowbuttolerablerfish,andatsunrisetheasterwillbegintobechargedb：thealgae.Onacloudyday,ofcourse,theagaewilgeneratemuchIessoxygcn,andtherewillbemuchlesstotideoverthepondpopulationatnight.Coolweatheralsowi11slowphotosy11-thesisslightly.Thef4chainisanothermajorforceatworkinthea+rntice11viron-ment.Asthetermimplies,al1lifeinthewaterislinkedtogether.ndeveryplantandanimalisdestinedtobeeatenbythebeingonthenexthigherlevelofthechain.Interest-ingly,acreaturessourceoffoodratherthanitssizeiswhatfixesitspositiononthefoodchain.Becausealgaemaketheirfoodfromgas,light,andwater,theyareatthefirstlevel.Andbecausesomeverylargefishfeeddirectlyonmicanedzoopfisharethemselvesquitelowonthedpond,itstheseplanktonfeedersthatwillgrowbestwiththeleastattentiontosupple-natdfoodsinthebecauselikegrassinasuppliedbynatureorbyyou,therewillbearichbloomofalgae.Andthealgalpoptionwillexpanduntilallfreenutrientsareal1ofthesefish,you11needcommercialfeedblends-readilyavaiIablefrom1ives-tockfeedsuppliers.Actually,togetbumpercropsof1It,ayfish,supple-mentingnaturalfoodsisnearlyal-waysessential.ThenextpointtorememberisIhzlifeedingatproductiveratesstimu-Iatesrapidgrowthandhigherwastelevels.Sincemoreoxygen8iiibeneededbythefast-growingushantoreadytheBystemtoabsorbtheirwastes,youmightneedtofertilizewithmanure.Thelife-givingnutrientsthusprovidedwillmultiplyal-gae,zooplankton,andbacteria,Thesewillfeedonthedetritusandprovidemoreoxygenandfeefish.Todetermineifyoudoneedtoaddfertilizer,thereisasimpletestyoucanmake.Ifyouralgaeareadequate,theyshouldbesothickthatyoucantseeanydeeperthan15to18inchesintothewater,Tofindoutifthisisso,marktheinchesoffstickandIai1atincanend.Thenushtheintothewatr=:untilfromsight.NextcheckthehighwIfthelidisvisyoushouldferti1izewithmanure.Foreachacreofpondsurface,use500)sndplacethemintheemanureifneeded,butbeManuringwillbemostsuccrssfulinpondswherewarmwaterfishwillgrow.Inlargepondswithwatr:rttlm-PtraturesbetweenFiO*FandIiOEyoumayhavetroubtogettingathickbhomofalgaeevenifyouaddmuchmanure.ButthenthetroutandolhtbrcoldwaterspeciesyouwouldgrowtherepreferCrwateranyway.Aerating:Youcansuppk'mt'titoxy-gencontributedbyairat!lalgaebypayingattentiontothetyenclosureyouchoose,toandtomechanicaldevicesthathelpoxygenexchange.Fori11stance,byimpoundingasectionofstreamwithIadamornetlikefence,youcantiak''afishfarmthatisalwaysbeingSUPPliedwithfreshlyoxygenatedwater.(Tbmbling,rollingfast-movingwaterbreaksintowavesCanclsplashesthattakemoreoxygenfromtheair.)Ifyoudofarmastreamorbrook,however,youwonteasilyreapthebenefitsoffertilization,fortheman-urewi11bewashedfardownstream.ThesamethingcanhappentoyourfishfoodunlessyoudeviseaStatio-naryfeederthatcanresistthecur-rent.Rememberthatyourwastedfeedorfertilizerispollut.i''foryourneighbordownstream.Andthatadd-ingthesematerialswithoutbeingsureoftheireffectsanddestinationisillegalaswel1aswasteful.AbettersystemwouIdbetotapaportionofthestreamwaterviaaorditch.Youmightmuteitthmuomal!pondbby,thenbacktotheBEtream,thekiarncpoten-tialproblemsexist,thiskindofsetupismoreeasilycontrolled,Youcanregulatetheamountofwaterandrateofflow.Andwhenstormsswe11thestreamwithwater,mud,andde-bris,youcandisconnectyourencto-W?.ofthestreamyounbycreatingasmallwaterfallorspillwayoverrocks.Thiswayyoucanchargea9smallamountofincomingwaterasitentersarelativelylargepool.Thiswateralsowillbringinsomeoxygen-makingalgaeandsomefishfoods.Iftheenclosureismuchlargerthanthestreamandmuchofthewaterremainswithinitforaweekorso,youmightencouragemorealgaewithtowlevelfertilization.Totakefulladvantageofaeration5ywind,makethesurfacearealargerratherthandeepenthewaterwhenyouwanttoincreaseyourpondsvchme.Also,autlocationswheretreesorbuiIdingswillkeepwindorsunfromthesurface.Thewatersurfaceshouldntlietoofarbelowthebankseither-especiallyinsmal1ponds.Insomepartsofthecountrymechanicalaeratorsmaybeneces-saryifyourestockingandfeedingapondforhigherproduction.Theamountofsupplementaryaerationyouneedwilldependuponyourpondsnaturaloxygenlevels-linked,ofcourse,towindandphotosynthesis-andonthequantityoffishyouvestockedpercubicfootofwater,Thoughmechanicalaeratingeasilyremovesanydoubtsaboutadequateoxygen,youdbeststartsmall,forthecostoftheaeratorandthepowertofuniteasilycanbecomeoneofyourbietexpensesinfishculture.Inverysmallgrandstrybubblingaerators-thekind(1,tenuwdinaquariumtarke,TheyarecheapandUIWrittkpov?r.Ina490"Square-footpond,trytwowithfouraerationtubesoneach.Inalargerpond,youmighthave:tousePurfaceaerators,whichchurnorspraythr*water.Fig-powerofaeratorforboostyourpondsoxygenduringthedogdaysofsummer.Thereasonisthatinsunnyandveryhotweatheralgaebegintogrowmuchmorevig-orouslythanusual.Thenwhtwcloudyandperhapsslightlycoolerweathersetsinforafewdays,oxy-genproductiondropssuddenly.Sincethewryhighoxygendcrnxctofthe*expandedpopulationcantbemet,somepond1ifewi11die.Thisisthetimewhenfishkillsaremostcommon,andinsomeplacestheyoccurregularlyonceortwiceaseason.Theproblemiswor;atnightawlishcightent'-rlbcte7ayofthedeadalgae,inasitu,rtionlikethis,a1/20h.p.aeratormaysupplyenoughoxygentosiIpportseveralhundredpoundsoffish,usingjustttsofpoweradayAt3centsakiIowatthour,12cenl9adayisasmal1pricetopayfortidingyourfishthrough.Anotherremedyifoxy-get7levelsbecomeperiIouslylowistoharvestaomcfish.Thiswillquicklyreducethedcmanoontheoxygensource,IPUTTIp:scINAkI$HPONDOneofthemissionsoftheSoi1ConservationServiceistohelpndsthatwilllast.SiSenkxalkxdkkmifyourprojectisforvnutodoyourself,ystateshaveIaiVSthatregu-latethewwofwaterandthedesignandconstructionofponds.Somere-q+ethatplansforadambeap-provedbyastateagencybeforeaconstructionpermitisgranted.Sobeforeyoustartbuildingapond,Endoutwhatlawsapplylocally.PriortotalkingwithanyoneattheSoilConservationService,you11wanttogiveyoursituationsomethought.Herearesomemajoras-pectstoconsiderandsometerh-niquesyoumightfinduseful.Selectingudte:Tofillyourpondandreplenishwaterlostbyevapora-tionandseepage,locateitnearade-pendableSOWCofgoodwater,P0+siblesourcesaresprings,wells,streams,andtherunofffromrain.Runoffistheleastdependable,andinareasof1ightrainfal1apondfilledbyrunoffmustbeoversizedtocarrythefishthroughdrought.Thesoi1atyoursite-lustbeabletoholdwater,oryouhavetosealthepondartificially.Clayandsiltyclayaregoodforwnds,andsandyclaysometimesholdswateradequately.Butareaswithrockout-croppings,limestone,shaleledges,orgravelrequiresealing.Foragoodpreliminarysoi1test,wetahandfulwithjustenoughwatertodampen.Thensqueeze.Ifthesoi1holdsitsshapeafteryouopenyourhand,itsprobablygoodforapond.Therearetwobasictypesofponds.Impoundingpondsarebestsuitedtohillyareas.Theyusedamsorbanksofearthtobloc：:offtheopeningbetweentwobanksorslopesandareusuallyeasiertobuildbe-cituselessearthmustbemoved.Mostofthereservoircreatedisabovethenaturalgroundlevel,thoughthesizeordepthcanbein-creasedbyexcavation.Excavatedpondsarepitsdugbelowthepondsurface,usuallywherelandisfairlyflat.Thereisnodefiniteruleforchoosingbetweenthetwotypes,Butifthelandsur-roundingyoursiteslopesmorethan4percent,animpoundingpondislikelytowork.Todeterminetheslope,driveastakeintoyoursiteatthehighestpointyouexpectthewatertoreach.Thendrivemotherstakeinabout10