HAWAU-G-99-004 C2 I.OAlilCOPV OSLO' Aquafarmer Information Sheet Spawning the tinfoil barb, Barbodes schINanenfeldi in Hawaii by Richard Bailey and Brian Cole Aquaculture Extension Agents, Sea Grant Extension Service School of Ocean and Earth Science and Technology, University of Hawaii Introduction or aviulability of niitural feeds phytoplankton and zooplank- ton! Ior the developingfry. The tinfoil barb,like other related The tinfoil barb, Brir/rodes sclivva»arly Mi, is a common species, is an cgg scattcrcr, laying eggs over a substrate such fish found in thc international aquarium trade and food mar- as plants or gravel to help hide and protect the eg s and larvae kets in Southeast Asia. Tinfoil barbs have a dorsal, ventrally from predators. f!attened body covered with moderately large, silver, chrome- Unfortunately, the tinfoil barb will not reproduce natu- like scales and rcd fins with a red leading fui ray Figure I!. rail> in a captive cnvironmcnt. Certain cnvironmcnta! cucs, Tinfoil barbsare a peacefulfish thatcan reacha lengthgreater suchas lunar phase, photopcriod, temperature, feeds, substrate, than 40 centimctcrs or 16 inches, and like other, larger barbs, cic,, stimulate a complex of'hormonal interactions that con- can often live morc than 10 years in captivity. In nature, tinfoil trol reproduction in fish. These environmental cucs inust be barbsare primarily macrophages;that is, they feed on vascu- presentfor most fish or the fish specieswill not matureand lar aquaticplants. However, they will cat mostconunercialfy spawn in captivity. Fortunately, the endocrine system of many prepared diets consisting of vegetable and fish meal proteins. fish is relatively well understood. Thc complex hormonal mechanismscontrolling matunition of'oocytes oocytes are Figure 1. maturingeggs inside thc femaleovaries; once spawned, they A Female arc called eggs! and ovulation in fish can be bypassedthrough induction with hormones. Ifhormoncs are administered to the tinfoil barb. fish by injection at the right time and dose, thc fish can be deceived into responding as though thc right environmental stiinuli are present.This will initiate a sequenceof natural hormonal changes that will lead to final oocyte maturation. ovulation and spawning. Some fish will naturally spawn eggs Thc genus Barbodesis closely related to the genera in captivity after hormone induction, while others must be Calioetaand Punriu» found in the subfamily Cyprininac.Thc "hand stripped" of eggs and milt. taxonomy of'these three gcncra are often treated as being syn- onymous.These closely relatedspecies inhabit the freshwater lakes, rivers and tributaries of Southeast Asia. Water quality Facilities parameters of the tinfoil barb's natural habitat ranges from soft to moderatelyhard water Cicrmanscale dH 5- 12', or 100to Successin hormonally inducedspawning in thc tinfoil 200 milligrams per liter [equivalent to parts pcr tnillion] cal- barb and other related species results from a good working cium carbonate!. pH of 6.5 to 7.0, and a temperature of 22 to knowledge ofhormone induction as well as adcquatc support 25 C [72' to 78 F]! Tinfoil barbsare a hardyfish that cando facilitics. Broodfish,holding hatchingand larval rearing tanks well in conditions exceeding the water quality parameters of are important to thc successof producing larvae. the i r natural habitat. Broodstock tanks or ponds should be large enough In I lawaii, tinfoil barbs become sexually mature from >1,000 gallons! to hold two to three times the number of May tlirough July during the onset of rising water tempera- broodstock required to produce the desired number of eggs. ture, 25' to 27'C 7' to III'F!. Many fish naturally spawn Two scparatc.static 50- to 150-gallonholding tanks during seasonalchanges, such as an increasein tcrnperature CTSA Publication Number 136 January 1999 Spawning the tinfoil barb Page 2 equipped with thermostatic controlled heirter s! are neededto the males by gently pinching thc fish between one's fingers and maintain a constant temperature to hold sexed broodstock fish sliding down the abdominalregion towardsthe anterior genital duringthe induction process. Fish are uoi fcdv hilc theyare in opening or papillae. whitish clear fluid or milt will come out of thc hoMingtanks. Static tank systemsv ork well if the density the rnafc'sgcnit;il papillaewhen it i» sexuallymature and ripe. is kept low, for example,I kilogram pcr 189 liter» or 4 to 5 Tinfoil barb»can achicvc»cxualmaturity by their first year. fish pcr 5 ! gallons. High w«ter quality shouldbc maintained I lowever, two-year-old fish are most commonly used for induced during spawning induction, spawningbecause they producea largernumber of eggsper spawn An cgg hatching systemthat consistsol a hatchingjar and often a grc«icr fertilization rate. Onc-year-oldtinfoi! barbs anda Iarv«1rearing tank is nccdcd.Usc of a flow-throughsys- canbe usedfor»pawning if the femaleshove f'ully developedoo- tem i» recominendcdto eliminatewater quality problems.IKc- cytcs and if the males show milt. Female tinfoil harb» 200 io 300 circulatingsystems are not rccom»iendedbecause they arenot gram»in sizecan produce5,000-plus eggs pcr»paivn. often biologically c»tablishcdand rcquirc additionalmanage- ment skills. Hatchingjar»ysteiiis require,on the avcragc,I to 2 liters per minute of water flow, basednn the egg density in Determining Female Maturity the jar. In Hawaii, I'emaletinfoil barbsbegin to developoocyte» in The larval rearingtank shouldbc largeenough to handle March or April and maturein IVlaythrough July. Farmersshould thc potentia!amount of !arvaefrom a spawn,For example,a harvest brood»tock from thc broodstock ponds and select a num- 30-gallon glass aquarium can hold two spawns of tinfoil barb ber of large femalesthat havevisibly well roundedabdominal re- larvae0,00 ! or 88 pcr liter! for a periodof'onc weekwith a gion or ovariesand weigh within approximately10 percent of each waterexchange rate nf 21itcrspcr minute 60 gallonspcr day other. The broodfish shouM bc handled gently, and their time out pcr tank! bctbre requiring a reductionin density. of water should be limited by pl ~cingthem into bucket »! with Conical fiberglassor acrylic tanks are now becoming quinaldinc for quinaldine mixture seeTable I !. Sedatingbrood morecommonly used duc to their improvedwater circulation fish helps limit »tres»«nd rn!ury during handling at this critical andefficient removalol wastes,which improveswater quiility stageprior to»pawning, and larval management. Determiningoocyte maturity rcquircs removing «»ample of oocytcs -30! from the ovariesot the fish using 1.14millimeter I.D. cannulatubing also called "microborc tubing" in chemical Broodstot:k supplycatalogs!. The tubing is madefrom flexib!c tygon. sihcon, One-year-oldflsli should bc isolatedf'rom growout fa- or polycthylcncmaterial that can be gently in»citedinto the gc»i- cilitiesand placed into separatebrood»tock rearing ponds or tal ventand movedup the oviductto the ovariesof'thc fish without I;irgetanks at a stockingdensity of 2 ki1ogramsper cubic meter causing injury. I fish per 25 gallons!. The fi»h arc kept at this density for a After the fish arecompletely sedated, which they exhibit by year io achievefully maturesize, to reduce»tressand discase being upsidedoivn and not reactiveto touch. they can bc staged prob!cm»,and to ensureproper nutrition and water quality, lor maturity.Thc cannulatubing shouldbc inscrtcd into the geni- Two brood»tock ponds or tank~ should bc maintained for each tal vent while gently tv i»tingand working thc tubedown ihc oi i- sex to ensurequality stock for spawningat a scx ratio of ai duct 2 to 3 inches to the ovary Figure 2!. Once in, the cannula least two malesto onc female. Broodfish should be given a shouldbe placedin th» farmer'smouth and gent!esuction should propercommercial dict consistingof at least30-plus percent be applied.The endof the tubing shou!iIbc held with one'sthumb protein in two or morerations ai a rateof I to 2 percentol'ih» while retractingthc tubecontaining the oocyte sample, which shoukl tot«l biomass weight TI3W! per day, Most commercial cat- be 30-plusoocytcs, from the fish, 'I' he fish shouldbe placedinto a lish and trout productiondiets are suitable,Floating feeds are numbered, aerated bucker that is marked "r! I. ' The fish will re- often used; these allow a farmer to oh»eree thc animals' feed- vive tully from thc quinaldine sedation within 2 to 5 minutes. ing response and gauge the population health. Placethe dry oocyte sampleon a graduatedglass micro- scope»lidc to determinethc oocyte'sdiameter. Ripe tinfoil barb oocytes are mature at«mean size of 1.12 millimctcrs. If the oo- Sexing Broodstock cytcsarc 1.12mill imetersin size,they shouldfir»t bc checkedfor Maturetwo-yc«r-old fish, 200 to 300 gramsin size,can overripeoocytcs, which can be distingui»hcdby the presenceof be visually sexedusing externalch iracteri»ties,Ripe Ii:male space betv een the oocytes' internal content and thc mcmbranc tuzforf barbs can bc identified by their»wollen abdominal re- Figurc 3!. indicatedby a withdrawa!of the oocyte'sinternal con- gion and smooth»cafes,M«lc fi»h are morc slenderin body tentsfrom ihc outcr wall. If the oocytcsarc not overripeand have shapeand havedi»tinctive rough tubcrcles pimple or sand- a good density,a couple of drops of "oocyte cgg clearing solu- p«pcr-like bumps! on their scales. One can extrude milt from tion" Table 2! shouId he added to the oocytes, ivhich will iillow the farmer to betterjudge migration of the nucleus.Vithi» 10 Center for Tropical and Subtropical Aquaculture Publication Number 136 January 1999 Spawning the tinfoil barb Page 3 n b c Figure 3. Oocyte staging a. Centered nuclei immature!; b. Off-center nucleus ripe!; c. Yolk materiai pulled away from oocyte wall overripe!. the middle or peaknl the seasona»d then taperingofT. Figure 2. Extracting oocytes from a tinfoil barb. Male Brood Fish Selection A sex ratio of one f'emalc to two male» v ill bc needed for artificial sp nvning.Thc I'armershould select large i»ales exhibiting roughtiiberclcs or scalesfrom the broodstocktank.