Gobiodon Citrinus, One of the "Coral Gobies" Most Popular Text & Photos: José María Cid Ruiz
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Gobiodon citrinus, one of the "coral gobies" most popular Text & photos: José María Cid Ruiz The genus Gobiodon (Perciformes, Gobiidae), comprises 31 species 1 of small gobies distributed over wide tropical areas of the Indian and Pacific oceans. They are small species (between 3 and 6.5 cm in total length), with arac"ve"v e co- lour paerns. These gobies typically live aachedhe d to brbran-an- ches and nooks of different corals both "hard"ha rd" (e.g. AcAcropo-ropo- ra spp ) as 'so#' (e.g. Sarcophyton sppsp p.).),, which rarely leave. Like all gobies, these specieses have merged its pelvic fins, ini n this way transformeded intoi nt o an organ of aachment, which allows them to remainr em ain strongly adhered to the surfacesurfac e of the coral, eevenve n in areas of strong current. They aarere sseden-ed en - tary fifishessh es with limited radius of ac%on,ac%o n, whichw hi ch basicallb as ic al lyy con-c on - sisistsst s in goingg oing ("jumping" rather thant ha n swimming)sw im mi ng ) fromfr om a ccoralor al branchbr an ch tot o anotheran other sec%on. TheseThes e gobiesgo bi es rarelyr ar el y leave its co- ral hostho st forf or venturingv en tu ri ng intoint o openop en waters.w at er s. TheyT he y are knoknownwn po- pularlypu la rl y as "coral"c or al gobies".g ob ies". is located in placespl ac as far apart as in northern and southern Japan, Samoa, Micronesia and AustraliaAu st ra (both south and north, in the Great Barrier Reef). G. citrinus present a small sizesi ze (6.5( 6. cm the larger specimens). Juveniles have bright yellowish tones (with some dar- GobiodonGo bi odon ccitrinus,it ri nu s, bbiologyio lo gy aandnd aacclima•za•oncc li ma •za•on to aquariumaquarium ker variaons according to geographic origin of the populaon in ques%on). With the age Onee of the speciess pe ci es mostm os t commonlyco mm only keptk ep t in aquariuma qu arium is GoGo-- their color darkens. In aquarium, some%mes they show a pale colour, due to any lack of biodonon citrinusc it ri nu s (Rüppell,(R üp pe ll, 1838).18 38 ). It is a species with largel ar ge dis- carotenoids in the diet, which does not provide the yellow pigment. tribu%onon areasa reas including:i nc lu di ng: southernso ut he rn Red Sea (Eritrea,(Er it re Ethio- The species show no appreciable sexual dimorphism with a naked eye. In nature, found pia) , the en%ren% re easte as t coastco ast of AfricaA fr ic a borderedbord er ed by the Indian in pairs or small groups. Ocean to Mozambique.oz am bi qu e. Addi%onally,Addi%onally , in the Pacific Ocean, it Gobiodon citrinus, oneo ne ofo f the "coral gobies" most popular 1 All rights reserved: ©José María Cid 2014 Field studies 2 have shown that these groups are led by a specimen that stands by their larger sizeze (a male) and several somewhat smaller specimensec im ens (all females). The species produces a toxicto xi c mucus 3 that covers its body and protectss themth em from being eaten by large predatory fishsh species. As already men"oned,ne d, its ac"vity is concentrated around coral hosth os t in which they live (mainly of the genus AcroporaAc ro pora ), rarely venturing into openo pe n wa-wa - tersrs (it( it iiss a species that has absolutelyabsol ut el y no swims wi m bladder).bl ad de r) . It isi s debated whether itsit s rela"onshipre la "o ns hi p withwi th thet he coralc or al isi s a symbiosissy mb io si s (arguing(a rg ui ng thatt ha t repelsre pe ls speciessp ec ie s whosewh os e feedfe ed isi s based on coralc or al polypsp ol yps and alsoal so wasw as verifiedv er ifi ed thatt ha t in thet he stomachsto ma ch contents of some speciess pe ci es ofo f thisth is genusg en us theret he re was filamentous algaeal ga e whichwhic h wouldwo ul d haveha ve injuredi nj ur ed tot o theth e coral). But othershe rs authorsautho rs believeb el ie ve thatt ha t it is a mildmi ld formf or m of pa- rasi"sm"s m (due tot o theyth ey foundf ou nd remainsr em ains ofo f coralco ra l polyps anda nd coralc or al mucusm uc us in itsit s stomachst om ach contents). Its bathymetricym etric distribu"ondi st ri bu "on4 rangesra ng es ffromrom 2 to 20 meters. Addi"onally, keep in mind that this is a vulnerable species when compe"ng with others species for food, since they rarely go to mid -waters in search of food. Therefore, it is very appropriate its ma- When planning itsit s maintenancema in te nance in cap"vity,c ap we intenance on aquariums dedicated to invertebrates, reef aquariums, aquariums with small and must remember ththatat tthishi s is a plank"vorousp la spe- quiet benthic species or directly keep them in specific aquariums targeted to its reproduc"on. cies and as such, requiresqu ir es a frequent feeding in small amounts. Some individuals may refuse to Regarding the size of the aquarium and despite its modest size and peaceful behavior towards accept frozen food ( Artemia, Mysis, Daphnia ) or others species, do not underes"mate its intraspecific aggressivity, because is common in small flake and requires a period of adaptaon of seve- aquariums, watch aggressions by ge$ng the best territories with corals placed strategically. ral weeks, during which you mix these foods with live crustaceans ( Artemia salina mainly). Gobiodon citrinus, one of the "coral gobies" most popular 2 All rights reserved: ©José María Cid 2014 Aquariums of 150 liters can accommodate a couple or a threesome properly. The aquarium should contem- plate living coral, preferably genus Acropora , or coral skeletons or ar!ficial corals, definitely an environment and a relief that reflect their natural habitat. Breeding in cap•vity G.citrinus is a hermaphrodi!c species. In nature, when a group loose its lider male, one of the females (generally the biggest) evolves into a male and starts lead the group again. This feature of their biology is useful for breeding in cap!vity, because if we acquirree a pair or trio, once well acclimated to the aquarium,ua ri um, iitt is highly likely that one of the specimens evolvee vo lve ttoo male, while the others remain as females.em al es. The reproduc!ve paern thatt ha t I have followed for this species was based on placingp la ci ng two groups of 6 speci- mens in two specificec ifi c aquariumsaq ua ri um s 30030 0 and 400 l respec-resp ec - !vely. The evolu!onvo lu !on of bothb ot h groupsgr ou ps wasw as similar,s im il ar , beingbe in g CohabitaonCo ha bi ta!on was stable in both groups over severalsever al montm hs without any casual!es took place. formed a$er ababoutout a momonthnt h a coupleco up le ini n bothbo th tankstan ks However, it was no!ceable certain level of sstresstr es in specimens living on the periphery of terri- (largest specimensme ns with brightbr ig ht colorful:c ol or fu l: reddishr ed di sh head tories defended in each aquarium by ononee of the couples. and lemon yellow tonest on es ono n flanks).fla nk s) . BothBo th couplesc ou pl es con-c on - - In aquarium, if they are well acclimatedac cl im and their quality of life is high, it is not uncommon to trol a preferen!al area,re a, wwherehere ttheyhe y ininteractte ra ct ttogether.og et he r. watch spawnings. My two couplesco began to make their first spawnings at about the same !me, The rela!onship betweenee n the componentsco mp on en ts ofo f eachea ch fourfo ur monthsm onths aer thet he ini!ali ni forma!on of the two groups. The species spawns on a branch of pair is large tolerance. Fromro m the epicenterep ic en te r of theirt he ir tte-e- ththee liliveve or arar!ficial!fi ci al coral which is the center of their territory. The female deposits the eggs in rritories, each pair is projectedte d to pursuep ur su e otherothe r speci-ec i- rows of cicircularrc ul outline, in an area that has previously been cleaned by the male. The male then mens, but in all cases were notno t long oro r obsessiveob se ssive perpe r-- prproceedsoc ee ds to fer!lize the eggs and cares about its surveillance un!l hatching. secu!on, as have been observeded in ototherhe r species.sp ecies. Gobiodon citrinus, one of the "coral gobies"ob ie s" mostm os t poppopuularla r 3 All rights reserved: ©José María Cid 2014 In my tanks despite the abundant corals and rocks providedde d (perhaps due to a failure in choosing the elements over the bo!om), they have o#en done the spawnings on the walls of the aquarium. Usuallyua ll y they have chosen li!le bit visi-vis i- ble and accessible locaons next to the centerce nt er of thetheirir territory (they have co- me to spawn on the curved glass of thet he heater).