Peaceful fish generally have a peaceful disposition and are an excellent inhabitant of a peaceful community tank. Peaceful fish should not be mixed with more aggressive fishes by beginner aquarists.The fish below are all peaceful.
Angelfishes
Basses (including Anthias, Groupers, & Hamlets)
Hypoplectrus gemma
Hypoplectrus guttavarius
Hypoplectrus indigo
Hypoplectrus nigricans
Hypoplectrus puella
Basslets, Spiny Basslets, & Grammas
Blennies and Blennylike Fishes
Acanthemblemaria spp
Atrosalarias fuscus
Crossosalarias macrospilus
Ecsenius bicolor
Ecsenius bimaculatus
Ecsenius gravieri
Ecsenius lineatus
Boxfishes, Puffers, and Triggerfishes
Butterflyfishes
Chaetodon argentatus
Chaetodon auriga
Chaetodon burgessi
Chaetodon collare
Chaetodon declivis
Chaetodon fasciatus
Chaetodon fremblii
Chaetodon guttatissimus
Chaetodon humeralis
Chaetodon kleinii
Chaetodon lineolatus
Chaetodon lunula
Chaetodon mertensii
Chaetodon mesoleucos
Cardinalfishes
Damselfishes (including Clownfishes)
Amphiprion akallopisos
Amphiprion bicinctus
Amphiprion leucokranos
Amphiprion nigripes
Amphiprion ocellaris
Dartfishes
Dragonets
Eels
Filefishes
Gobies
Amblyeleotris diagonalis
Amblyeleotris guttata
Amblyeleotris steinitzi
Amblyeleotris wheeleri
Amblygobius decussatus
Amblygobius phalaena
Amblygobius rainfordi
Coryphopterus glaucofraenum
Coryphopterus personatus
Cryptocentrus aurora
Cryptocentrus cinctus
Cryptocentrus pavoninoides
Ctenogobiops tangaroai
Grunts & Sweetlips
Hawkfishes
Rabbitfishes
Seahorses & Pipefishes
Squirrelfishes, Soldierfishes, Bigeyes & Catalufas
Tangs & Surgeonfishes
Acanthurus coeruleus
Acanthurus dussumieri
Acanthurus fowleri
Acanthurus japonicus
Acanthurus olivaceous
Acanthurus tennentii
Acanthurus thompsoni
Wrasses, Hogfishes, & Tuskfishes
Anampses chrysocephalus
Anampses meleagrides
Bodianus bimaculatus
Cetoscarus bicolor
Cirrhilabrus aurantidorsalis
Cirrhilabrus balteatus
Cirrhilabrus bathyphilus
Cirrhilabrus condei
Cirrhilabrus cyanopleura
Cirrhilabrus exquisitus
Cirrhilabrus filamentosus
Cirrhilabrus aurantidorsalis
Cirrhilabrus laboutei
Cirrhilabrus linneatus
Cirrhilabrus lubbocki
Cirrhilabrus luteovittatus
Cirrhilabrus punctatus
Cirrhilabrus pylei
Cirrhilabrus rhomboidalis
Cirrhilabrus rubrimarginatus
Cirrhilabrus rubripinnis
Cirrhilabrus rubrisquamis
Cirrhilabrus rubriventralis
Cirrhilabrus scottorum
Cirrhilabrus solorensis
Cirrhilabrus temminckii
Cirrhilabrus tonozukai
Halichoeres chloropterus
Halichoeres chrysus
Halichoeres garnoti
Halichoeres hortulanus
Halichoeres iridis
Halichoeres melanurus
Halichoeres ornatissimus
Halichoeres trispilus
Hemigymnus melapterus
Labroides dimidiatus
Labroides phthirophagus
Macropharyngodon bipartitus
Macropharyngodon choati
Macropharyngodon geoffroy
Macropharyngodon meleagris
Macropharyngodon negrosensi
Paracheilinus carpenteri
Paracheilinus filamentosus
Paracheilinus mccoskeri
Paracheilinus octotaenia
Scarus taeniopterus
Wetmorella nigropinnata
Semi-aggressive fish in the wild occupy the predator niche on the reef and are fully capable of aggressive behavior in a tank. Beginning aquarists should not mix aggressive species with peaceful species. If they are to be mixed, the more aggressive animal should be added later in the stocking order. The fish below are all semi-aggressive.
Angelfishes
Apolemichthys trimaculatus
Apolemichthys xanthopunctatus
Centropyge acanthops
Centropyge argi
Centropyge aurantia
Centropyge aurantonotus
Centropyge bicolor
Centropyge bispinosa
Centropyge colini
Centropyge eibli
Centropyge fisheri
Centropyge heraldi
Centropyge interruptus
Centropyge loricula
Centropyge multicolor
Centropyge multifasciatus
Centropyge multispinis
Centropyge nox
Centropyge tibicen
Centropyge vrolikii
Chaetodontoplus caeruleopunctatus
Chaetodontoplus conspicillatus
Chaetodontoplus mesoleucus
Chaetodontoplus septentrionalis
Holacanthus bermudensis
Holacanthus ciliaris
Holacanthus passer
Holacanthus tricolor
Pomacanthus annularis
Pomacanthus arcuatus
Pomacanthus asfur
Pomacanthus chrysurus
Pomacanthus imperator
Pomacanthus maculosus
Pomacanthus navarchus
Pomacanthus paru
Pomacanthus semicirculatus
Pomacanthus sexstriatus
Pomacanthus xanthometopon
Pomacanthus zonipectus
Pygoplites diacanthus
Pygoplites diacanthus (Red Sea)
Anglerfishes & Frogfishes
Basses (including Anthias, Groupers, & Hamlets)
Blennies & Blennylike Fishes
Boxfishes, Puffers, & Triggerfishes
Arothron diadematus
Arothron hispidus
Arothron immaculatus
Arothron manilensis
Arothron mappa
Arothron meleagris
Arothron nigropunctatus (Dog Face)
Arothron nigropunctatus (Yellow Belly)
Arothron stellatus
Butterflyfishes
Damselfishes (including Clownfishes)
Abudefduf saxatilis
Amblyglyphidodon aureus
Amphiprion allardi
Amphiprion chrysopterus
Amphiprion clarkii
Amphiprion melanopus
Amphiprion perideraion
Amphiprion polymnus
Amphiprion polymnus (black)
Amphiprion polymnus (brown)
Amphiprion sandaracinos
Amphiprion sebae
Dottybacks & Pseudochromis
Cypho purpurascens
Labracinus cyclophthalmus
Pseudochromis aldabraensis
Pseudochromis cyanotaenia
Pseudochromis dilectus
Eels
Grunts & Sweetlips
Hawkfishes
Lionfishes
Tangs & Surgeonfishes
Acanthurus achilles
Acanthurus bariene
Acanthurus blochii
Acanthurus chirurgus
Acanthurus guttatus
Acanthurus maculiceps
Aggressive fish are fishes that, by nature, prey on other animals in the aquarium by nipping or eating their prey whole. The fish below are all aggressive.
Basses (including Anthias, Groupers, & Hamlets)
Cephalopholis argus
Cephalopholis formosa
Cephalopholis fulva
Cephalopholis miniata
Cephalopholis polleni

Apolemichthys griffisi
Chaetodontoplus duboulayi
Chaetodontoplus melanosoma
Chaetodontoplus meredithi
Genicanthus bellus
Genicanthus caudovittatus
Genicanthus lamarck
Genicanthus melanosplilos
Genicanthus semifasciatus
Genicanthus watanabei
Hypoplectrus unicolor
Plectranthias inermis
Pseudanthias bartlettorum
Pseudanthias dispar
Pseudanthias fasciatus
Pseudanthias kashiwae
Pseudanthias parvirostris
Pseudanthias pulcherrimus
Pseudanthias randalli
Serranocirrhitus latus
Assessor flavissimus
Assessor macneilli
Gramma loreto
Gramma melacara
Liopropoma rubre
Liopropoma swalesi
Serranus tortugarum
Platax orbicularis
Platax pinnatus
Platax teira
Ecsenius lividanalis
Ecsenius melarchus
Ecsenius midas
Ecsenius namiyei
Ecsenius stigmatura
Entomacrodus marmoratus
Istiblennius chrysospilos
Meiacanthus mossambicus
Meiacanthus nigrolineatus
Pholidichthys leucotaenia
Salarias fasciatus
Salarias ramosus
Salarias segmentatus
Anoplocapros lenticularis
Aracana aurita
Lactoria cornuta
Ostracion meleagris
Ostracion cubicus
Ostracion whitleyi
Tetrosomus gibbosus
Chaetodon miliaris
Chaetodon paucifasciatus
Chaetodon pelewensis
Chaetodon punctatofasciatus
Chaetodon rafflesii
Chaetodon rainfordi
Chaetodon semilarvatus
Chaetodon tinkeri
Chaetodon trichrous
Chaetodon ulietensis
Chaetodon unimaculatus
Chaetodon wiebeli
Chaetodon xanthurus
Chelmon marginalis
Chelmon muelleri
Chelmon rostratus
Coradion altivelis
Forcipiger flavissimus
Forcipiger longirostris
Hemitaurichthys polylepis
Hemitaurichthys zoster
Heniochus acuminatus
Heniochus intermedius
Heniochus singularius
Heniochus varius
Prognathodes aculeatus
Apogon cyanosoma
Apogon leptacanthus
Pterapogon kauderni
Sphaeramia nematoptera
Sphaeramia orbicularis
Amphiprion ocellaris (Black & White)
Chromis analis
Chromis cyanea
Chromis margaritifer
Chromis nitida
Chromis retrofasciata
Chromis scotti
Chromis vanderbilti
Chromis viridis
Gunnelichthys curiosus
Nemateleotris decora
Nemateleotris helfrichi
Nemateleotris magnifica
Parioglossus raoi
Ptereleotris evides
Ptereleotris heteroptera
Ptereleotris zebra
Dactylopus dactylopus
Synchiropus ocellatus
Synchiropus picturatus
Synchiropus splendidus
Synchiropus stellatus
Taenioconger hassi
Cantherhines dumerilii
Chaetodermis pencilligerus
Meuschenia hippocrepis
Oxymonacanthus longirostris
Paraluteres prionurus
Paramonacanthus japonicus
Pervagor melanocephalus
Pervagor spilosoma
Parupeneus cyclostomus
Parupeneus barberinoides
Parupeneus multifasciatus
Discordipinna griessingeri
Elacatinus horsti
Elacatinus multifasciatus
Elacatinus puncticulatus
Gobiodon ceramensis
Gobiodon cetrinus
Gobiodon histrio
Gobiodon okinawae
Gobiosoma evelynae
Gobiosoma oceanops
Lythrypnus dalli
Lythrypnus zebra
Paragobiodon lacunicolus
Priolepsis nocturna
Signigobius biocellatus
Stonogobiops nematodes
Stonogobiops yashia
Trimma cana
Valenciennea helsdingenii
Valenciennea longipinnis
Valenciennea puellaris
Valenciennea sexguttata
Valenciennea strigata
Valenciennea wardii
Cirrhitichthys falco
Opistognathus rosenblatti
Opistognathus aurifrons
Siganus corallinus
Siganus doliatus
Siganus guttatus
Siganus magnificus
Siganus puellus
Siganus punctatus
Siganus spinus
Siganus unimaculatus
Siganus uspi
Siganus virgatus
Siganus vulpinus
Aeoliscus strigatus
Corythoichthys haematopterus
Siganus dactyliophorus
Doryrhamphus excisus
Doryrhamphus multiannulatus
Siganus abdominalis
Hippocampus kuda
Caesio xanthonota
Lutjanus sebae
Macolor niger
Symphorichthys spilurus
Heteropriacanthus cruentatu
Myripristis vittata
Myripristis jacobus
Sargocentron tiere
Sargocentron xantherythrum
Acanthurus triostegus
Ctenochaetus hawaiiensis
Ctenochaetus strigosus
Ctenochaetus tominiensis
Ctenochaetus truncatus
Naso brevirostris
Naso elegans
Naso literatus
Naso unicornis
Naso vlamingii
Paracanthurus hepatus (blue)
Paracanthurus hepatus (yellow)
Zebrasoma scopas
Hoplolatilus chlupatyi
Hoplolatilus marcosi
Hoplolatilus purpureus
Hoplolatilus starcki
Antennarius commerson
Antennarius maculatus
Antennarius striatus
Histrio histrio
Nemanthias carberryi
Paranthias furcifer
Pseudanthias bicolor
Pseudanthias cooperi
Pseudanthias huchtii
Pseudanthias lori
Pseudanthias pictilis
Pseudanthias pleurotaenia
Pseudanthias rubrizonatus
Pseudanthias squamipinnis
Pseudanthias truncatus
Calloplesiops altivelis
Gramma brasiliensis
Serranus baldwini
Exallias brevis
Meiacanthus atrodorsalis
Meiacanthus grammistes
Meiacanthus oualenensis
Meiacanthus smithi
Meiacanthus tongaensis
Parablennius marmoreus
Parapercis schauislandii
Canthigaster bennetti
Canthigaster coronata
Canthigaster epilampra
Canthigaster jactator
Canthigaster valentini
Chilomycterus schoepfii
Diodon holocanthus
Melichthys niger
Melichthys vidua
Odonus niger
Sufflamen albicaudatum
Sufflamen bursa
Xanthichthys auromarginatus
Xanthichthys caeruleolineatus
Xanthichthys mento
Xanthichthys ringens
Chaetodon ephippium
Chaetodon falcula
Chaetodon melannotus
Chaetodon mitratus
Chaetodon nippon
Chaetodon vagabundus
Apogon maculatus
Apogon novemfasciatus
Amphiprion tricinctus
Chrysiptera cyanea
Chrysiptera galba
Chrysiptera hemicyanea
Chrysiptera parasema
Chrysiptera rollandi
Chrysiptera springeri
Chrysiptera starcki
Chrysiptera talboti
Dascyllus aruanus
Dascyllus marginatus
Dascyllus melanurus
Dascyllus reticulatus
Dascyllus trimaculatus
Dascyllus trimaculatus (Gold)
Neoglyphidodon nigroris/a>
Pomacentrus alleni
Pomacentrus auriventris
Pomacentrus bankanensis
Pomacentrus moluccensis
Pomacentrus smithi
Pseudochromis elongatus
Pseudochromis flavivertex
Pseudochromis fuscus
Pseudochromis paccagnellae
Pseudochromis polynemus
Pseudochromis porphyreus
Pseudochromis splendens
Pseudochromis springeri
Pseudochromis veliferus
Echidna nebulosa
Echidna polyzona
Gymnomuraena zebra
Gymnothorax kidako
Gymnothorax melatremus
Gymnothorax meleagris
Gymnothorax miliaris
Gymnothorax miliaris (Gold)
Gymnothorax nudivomer (Gold)
Myrichthys maculosus (Gold)
Rhinomuraena quaesita
Amblyeleotris randalli
Amblygobius semicinctus
Cryptocentrus leptocephalus
Plectorhinchus albovittatus
Plectorhinchus chaetodonoides
Plectorhinchus diagrammus
Plectorhinchus lineatus
Plectorhinchus orientalis
Plectorhinchus picus
Amblycirrhitus pinos
Cirrhitichthys aprinus
Cyprinocirrhites polyactis
Neocirrhites armatus
Oxycirrhites typus
Dendrochirus biocellatus
Dendrochirus brachypterus
Dendrochirus zebra
Pterois antennata
Pterois radiata
Pterois volitans
Acanthurus mata
Acanthurus nigricans
Acanthurus nigrofuscus
Acanthurus nigroris
Acanthurus pyroferus
Acanthurus tristis
Ctenochaetus binotatus
Zebrasoma desjardinii
Zebrasoma flavescens
Zebrasoma gemmatum
Zebrasoma rostratum
Zebrasoma veliferum
Anampses twistii
Bodianus anthioides
Bodianus axillaris
Bodianus bilunulatus
Bodianus masudai
Bodianus opercularis
Bodianus pulchellus
Bodianus rufus
Choerodon fasciatus
Choerodon jordani
Cirrhilabrus jordani
Clepticus parrae
Halichoeres bivittatus
Halichoeres radiatus
Novaculichthys macrolepidotus
Thalassoma bifasciatum
Thalassoma hebraicum
Thalassoma jansenii
Thalassoma rueppellii
Apolemichthys xanthurus
Centropyge flavissima
Cephalopholis urodeta
Chromileptes altivelis
Epinephelus flavocaeruleus
Epinephelus summana
Grammistes sexlineatus
Mycteroperca rosacea
Plectropomus laevis
Pogonoperca punctata
Variola albimarginata
Variola louti
Serranus tabacarius
Serranus tigrinus
Ophioblennius atlanticus
Abalistes stellaris
Balistapus undulatus
Balistes punctatus
Balistes vetula
Balistoides conspicillum
Pseudobalistes fuscus
Rhinecanthus aculeatus
Rhinecanthus assasi
Rhinecanthus rectangulus
Rhinecanthus verrucosus
Sufflamen chrysopterum
Amphiprion ephippium
Amphiprion frenatus
Chrysiptera taupou
Chrysiptera tricincta
Dascyllus albisella
Hypsypops rubicunda
Microspathodon chrysurus
Neoglyphidodon melas
Neoglyphidodon oxyodo
Plectroglyphidodon lacrymatus
Pomacentrus coelestis
Pomacentrus vaiuli
Premnas biaculeatus
Congrogadus subduscens
Pseudochromis diadema
Enchelycore pardalis
Gymnothorax favagineus
Gymnothorax fimbriatus
Gymnothorax funebris
Cirrhitichthys oxycephalus
Paracirrhites arcatus
Paracirrhites forsteri
Acanthurus leucocheilus
Acanthurus lineatus
Acanthurus monroviae
Acanthurus sohal
Zebrasoma xanthururm
Bodianus diana
Bodianus loxozonus
Bodianus mesothorax
Cheilinus lunulatus
Coris aygula
Coris formosa
Coris gaimard
Gomphosus varius
Novaculichthys taeniourus
Thalassoma hardwicke
Thalassoma lucasanum
Thalassoma lunare
Thalassoma lutescens
Thalassoma purpureum
Thalassoma quinquevittatum