U-mark sandperchParapercis snyderi
U-spot wrasseHalichoeres stigmaticus
UaruUaru amphiacanthoides
Ucamara catfishLepthoplosternum ucamara
Ucayali catfishLepthoplosternum altamazonicum
Ucayali striped pimPimelodella hartwelli
Uganda nothobranchNothobranchius ugandensis
Ukkrit's pygmygobyTrimma ukkriti
Ukrainian brook lampreyEudontomyzon mariae
Ukrainian gudgeonGobio sarmaticus
Umatilla daceRhinichthys umatilla
Umbrella cichlidApistogramma borellii
Umbrella congerGnathophis umbrellabius
uMkhomazi mountain catfishAmphilius zuluorum
Umpire TriplefinEnneapterygius rhabdotus
Umpqua daceRhinichthys evermanni
Umpqua pikeminnowPtychocheilus umpquae
UmpquachubOregonichthys kalawatseti
Umzimkhulu redfinPseudobarbus kubhekai
Unarmed dwarf monocle breamParascolopsis inermis
Uncombed blennyHaptoclinus apectolophus
Undistinguished sabretoothOdontostomops normalops
Undulate rayRaja undulata
GameUndulated morayGymnothorax undulatus
Unicolor coralgobyGobiodon unicolor
Unicolor morayEchidna unicolor
Unicolor snake morayUropterygius concolor
Unicorn codBregmaceros mcclellandi
Unicorn crestfishEumecichthys fiski
Unicorn grenadierCoelorinchus productus
Unicorn icefishChannichthys rhinoceratus
Unicorn leatherjacket filefishAluterus monoceros
GameUnicorn soleAesopia cornuta
UnicornfishLophotus capellei
Union snookCentropomus unionensis
GameUnipa chromisChromis unipa
Unipore snailfishParaliparis impariporus
Unpolished dwarfgobyEviota irrasa
Unspecked hardyheadCraterocephalus fulvus
Upjaw barbCoptostomabarbus wittei
Upland bullyGobiomorphus breviceps
Upper Grijalva livebearerPoeciliopsis hnilickai
Upper Yenisei graylingThymallus svetovidovi
Upper Zambezi labeoLabeo lunatus
Upper Zambezi squeakerSynodontis woosnami
Upper Zambezi yellowfishLabeobarbus codringtonii
GameUpside-down gobyBryaninops nexus
Upside-down pipefishHeraldia nocturna
Upsidedown catfishSynodontis batensoda
Upturned snout rattailCoelorinchus mycterismus
Upwelling dwarfgobyEviota algida
Ural gudgeonGobio uralensis
Uranoscopus fuscomaculatus
Uranoscopus turbisquamatus
Urchin clingfishDellichthys morelandi
Urmia Lake chubAcanthobrama urmianus
Urolophus neocaledoniensis
Ursinoscorpaenopsis kitai
Urucu coryCorydoras urucu
Uruguay river spratRamnogaster melanostoma
Uruguay tetraCheirodon interruptus
Uruguayan eartheaterGymnogeophagus australis
Urville's longtomStrongylura urvillii
Usangu lampeyeLacustricola usanguensis
Ussuri catfishTachysurus ussuriensis
Ussuri sharpbellyHemiculter lucidus
Usumacinta buffaloIctiobus meridionalis
Usumacinta cichlidKihnichthys ufermanni
Usumacinta mollyPoecilia kykesis
Usumacinta sea catfishPotamarius usumacintae
Usumacinta toothcarpPseudoxiphophorus obliquus
Uswanas' damselfishChrysiptera uswanasi
Utah Lake sculpinCottus echinatus
Utah suckerCatostomus ardens
Utchee rainbowfishMelanotaenia utcheensis
Utiaritichthys esguiceroi
Utiaritichthys longidorsalis
Utiaritichthys sennaebragai