How we wrote this
We write from primary sources, in this order of preference: peer-reviewed marine science, then Randy Holmes-Farley's Reefkeeping chemistry series, then named talks and manufacturer lab data, and only then named forum contributors. Plain community consensus is used last and labelled as such.
Where the hobby genuinely disagrees, we present both sides and name the proponents rather than pretend there's one answer. Each page shows the date it was last checked against its sources, and corrections to published facts are logged publicly. Read the full method.
What reef safe means
A reef tank holds a lot more than fish: stony and soft corals, anemones, clams, feather dusters, cleaner and peppermint shrimp, snails and crabs. A reef-safe fish is one that leaves all of that alone. Two things the label does not tell you: whether the fish gets along with other fish (a maroon clownfish is rated reef compatible and has an aggressive temperament), and whether it suits your tank's size. The table gives a minimum tank for each fish: the figure our tank-size pages use, which is sometimes more conservative than the vendor's, or the vendor's own where we have no page.
Ratings also come with conditions. "Mostly" and "with caution" usually mean an individual fish, or a hungry one, may pick at polyps or small invertebrates. The wording below is the source's, condensed; follow the links for the full context.
Reef safe
Rated safe with corals and invertebrates by the sources below. Several carry a small caveat, usually about tiny crustaceans or a hungry fish.
| Fish | What the sources say | Min. tank |
|---|---|---|
| Ocellaris clownfish Amphiprion ocellaris | Yes; without an anemone it may host in a coral (Microcosm Aquarium Explorer; WetWebMedia) | 20 gal |
| Clarkii clownfish Amphiprion clarkii | LiveAquaria rates it reef compatible, with a semi-aggressive temperament. (LiveAquaria) | 30 gal |
| Maroon clownfish Premnas biaculeatus | LiveAquaria rates it reef compatible, with an aggressive temperament. (LiveAquaria) | 55 gal |
| Green chromis Chromis viridis | Yes (LiveAquaria) | 55 gal |
| Yellow watchman goby Cryptocentrus cinctus | Yes; Biota says it won't bother corals or sessile invertebrates (Bulk Reef Supply; The Biota Group) | 20 gal |
| Firefish Nemateleotris magnifica | Yes (LiveAquaria) | 20 gal |
| Diamond goby Valenciennea puellaris | Yes (LiveAquaria; Quality Marine) | 55 gal |
| Midas blenny Ecsenius midas | LiveAquaria rates it reef compatible, though it has been known to nip at firefish and gobies. (LiveAquaria) | 50 gal |
| Tailspot blenny Ecsenius stigmatura | Generally yes; a few owners report it plucking at large-polyp corals (LiveAquaria; Meerwasser-Lexikon) | 10 gal |
| Starry blenny Salarias ramosus | Yes (LiveAquaria) | 30 gal |
| Royal gramma Gramma loreto | Yes; may eat hitchhiking amphipods (LiveAquaria; The Biota Group) | 30 gal |
| Banggai cardinalfish Pterapogon kauderni | Yes; inoffensive to corals and other sessile invertebrates (Jeff Kurtz) | 30 gal |
| Mandarin dragonet Synchiropus splendidus | Yes; no threat to corals or invertebrates (Microcosm Aquarium Explorer; Bulk Reef Supply) | 75 gal |
| Six-line wrasse Pseudocheilinus hexataenia | Yes; it hunts tiny crustaceans, not corals (LiveAquaria; FishBase) | 30 gal |
| Yellow tang Zebrasoma flavescens | Yes; a grazing herbivore (LiveAquaria; FishBase) | 100 gal |
| Kole tang Ctenochaetus strigosus | Yes; Quality Marine notes it may pick at invertebrates if underfed (Jeff Kurtz; Reefs.com; Quality Marine) | 75 gal |
| Tomini tang Ctenochaetus tominiensis | LiveAquaria rates it reef compatible; aggressive toward other tangs, peaceful with other fish. (LiveAquaria) | 75 gal |
| Powder blue tang Acanthurus leucosternon | Quality Marine calls it reef safe but says it may pick at small mobile and sessile invertebrates if not well fed. (Quality Marine) | 180 gal |
Reef safe with caution
Kept in reef tanks all the time, but each has a known habit: nipping coral polyps, picking at clams and feather dusters, or eating shrimp and small fish.
| Fish | What the sources say | Min. tank |
|---|---|---|
| Clown goby Gobiodon spp. (G. okinawae, G. histrio and others) | Mostly; may nip small SPS polyps and clear tissue to spawn (LiveAquaria; Tropical Fish Hobbyist) | 10 gal |
| Lawnmower blenny Salarias fasciatus | Mostly; some individuals nip invertebrates (Scott W. Michael; Jeff Kurtz; Meerwasser-Lexikon) | 40 gal |
| Melanurus wrasse Halichoeres melanurus | LiveAquaria gives no rating, but says it eats fireworms and pyramidellid snails, protecting corals and clams, and may also eat feather dusters, wild shrimp, tubeworms and flatworms. (LiveAquaria) | 75 gal |
| Blue hippo tang Paracanthurus hepatus | Mostly; if underfed it may pick at small invertebrates or corals (Meerwasser-Lexikon names Xenia and Acropora) (Tropical Fish Hobbyist; LiveAquaria; Quality Marine; Meerwasser-Lexikon) | 180 gal |
| Foxface rabbitfish Siganus vulpinus | With caution: nips LPS and soft coral polyps, mostly when underfed (LiveAquaria; Jeff Kurtz) | 125 gal |
| Flame angelfish Centropyge loriculus | With caution: may nip stony and soft corals, sessile inverts and clam mantles (LiveAquaria) | 70 gal |
| Coral beauty angelfish Centropyge bispinosa | LiveAquaria: reef compatible with caution, and prone to nip at stony and soft corals. (LiveAquaria) | 70 gal |
| Copperband butterflyfish Chelmon rostratus | LiveAquaria: reef compatible with caution; it may pick on invertebrates, especially anemones and feather dusters, and is used to control Aiptasia. (LiveAquaria) | 130 gal |
| Longnose hawkfish Oxycirrhites typus | LiveAquaria: reef compatible with caution; it eats small fish and shrimp. (LiveAquaria) | 50 gal |
| Volitan lionfish Pterois volitans | LiveAquaria: reef compatible with caution; it may eat smaller fish, shrimp and other crustaceans, and its fin spines are venomous. (LiveAquaria) | 120 gal |
Not reef safe
Rated not reef compatible: these eat the invertebrates a reef is built from.
| Fish | What the sources say | Min. tank |
|---|---|---|
| Picasso triggerfish Rhinecanthus aculeatus | LiveAquaria: not reef compatible. Its diet includes clams, small fish and hard-shelled shrimp. (LiveAquaria) | 180 gal |
| Dogface puffer Arothron nigropunctatus | LiveAquaria: not reef compatible; it will eat invertebrates found in a reef tank. (LiveAquaria) | 150 gal |
Reef-safe fish for small tanks
Filtering the reef-safe group to fish whose minimum tank is 30 gallons or less leaves 9: tailspot blenny (10 gal), firefish (20 gal), ocellaris clownfish (20 gal), yellow watchman goby (20 gal), banggai cardinalfish (30 gal), clarkii clownfish (30 gal), royal gramma (30 gal), six-line wrasse (30 gal) and starry blenny (30 gal). Small is not the same as easy: LiveAquaria and Bulk Reef Supply give the mandarin dragonet a 30 gallon minimum, but it lives on live copepods, so we use a more conservative 75 gallons. The stocking calculator checks a whole list against your tank.
Reef safe is not the same as peaceful
Most of the trouble in a reef tank is fish against fish. The common conflicts among the fish above:
- Tangs with tangs. LiveAquaria says the powder blue is extremely aggressive toward other tangs and should generally be the only one in the tank, and Quality Marine says Acanthurus tangs are known to be aggressive toward similarly shaped tangs.
- Clownfish with other clownfish. Keep one species, as a single fish or a pair; our stocking calculator flags any mix.
- Predators with small fish. LiveAquaria says the longnose hawkfish eats small fish and shrimp, and the volitan lionfish may eat smaller fish, shrimp and other crustaceans.
- The midas blenny with gobies. LiveAquaria says it has been known to nip at firefish and gobies.
The saltwater fish compatibility chart runs every pair of popular fish through the same checks.
Making the caution fish work
- Feed them well. Several cautions are explicitly about hunger: Quality Marine says the powder blue and kole may pick at invertebrates if underfed, and the foxface care sheet notes it nips coral polyps mostly when underfed.
- Expect individuals to differ. The lawnmower blenny's rating is "mostly" because some individuals nip invertebrates, and a few tailspot blenny owners report plucking at large-polyp corals.
- Weigh the trade-off. The copperband is the classic case: it may eat your feather dusters, and it may also clear your Aiptasia. The flame angel's caution covers clam mantles, so it is a poor choice for a tank built around clams.
- Quarantine everything. A reef display can't be treated with copper, so new fish go through a quarantine tank first.
People also ask
- What does reef safe mean?
- That a fish is not expected to eat or damage corals and invertebrates such as shrimp, snails, clams and feather dusters. There is no standard or certification; it is a judgement published by retailers, wholesalers and authors, often with conditions.
- Are clownfish reef safe?
- Yes. LiveAquaria rates clarkii and maroon clownfish reef compatible, and the ocellaris is reef safe, though without an anemone it may host in a coral. Mixing clownfish species is the problem, not corals.
- Are tangs reef safe?
- Mostly. Yellow, kole and tomini tangs are rated reef safe, and Quality Marine calls the powder blue reef safe but says it may pick at small invertebrates if not well fed; the blue hippo tang is reef safe with the same caveat. Tangs are aggressive toward each other, which matters more.
- Are dwarf angelfish reef safe?
- Only with caution. LiveAquaria says the coral beauty is prone to nip at stony and soft corals, and the flame angelfish may nip stony and soft corals, sessile invertebrates and clam mantles.
- Is a copperband butterflyfish reef safe?
- With caution. LiveAquaria says it may pick on invertebrates, especially anemones and feather dusters, but it is widely used to control Aiptasia.
- What is the best reef-safe fish for a small tank?
- Among the fish rated reef safe here, those our tank-size figures put at 30 gallons or less are: tailspot blenny (10 gal), firefish (20 gal), ocellaris clownfish (20 gal), yellow watchman goby (20 gal), banggai cardinalfish (30 gal), clarkii clownfish (30 gal), royal gramma (30 gal), six-line wrasse (30 gal), starry blenny (30 gal).
- Which saltwater fish are not reef safe?
- Of the fish on this list, LiveAquaria rates the Picasso triggerfish and the dogface puffer not reef compatible; the puffer will eat invertebrates found in a reef tank. Lionfish and the longnose hawkfish are rated with caution because they eat shrimp and small fish.
Sources & references
- 1.Microcosm Aquarium Explorer — Ocellaris clownfishhttps://en.microcosmaquariumexplorer.com/wiki/Ocellaris_Clownfish
- 2.WetWebMedia — Clownfish and anemone FAQs (crew replies)https://wetwebmedia.com/clnanemfaq2.htm
- 3.LiveAquaria — Clarkii clownfishhttps://www.liveaquaria.com/products/clarkii-clownfish
- 4.LiveAquaria — Maroon clownfishhttps://www.liveaquaria.com/products/maroon-clownfish
- 5.LiveAquaria — Green reef chromis (retailer care sheet)https://www.liveaquaria.com/product/115/?pcatid=115
- 6.Bulk Reef Supply — How to care for watchman gobies (2025)https://www.bulkreefsupply.com/content/post/how-to-care-for-watchman-gobies
- 7.The Biota Group — Yellow watchman goby (captive-bred, product page)https://shop.thebiotagroup.com/products/yellow-watchman-goby
- 8.LiveAquaria — Firefish goby (retailer care sheet)https://www.liveaquaria.com/product/168/?pcatid=168
- 9.LiveAquaria — Diamond watchman goby (retailer care sheet)https://www.liveaquaria.com/product/220/?pcatid=220
- 10.Quality Marine — Diamond goby (wholesaler care sheet)https://www.qualitymarine.com/valenciennea/diamond-watchman-goby-14521/
- 11.LiveAquaria — Clown goby, yellow (retailer care sheet)https://liveaquaria.com/product/1441/clown-goby-yellow
- 12.Tropical Fish Hobbyist — Gobiodon histriohttps://www.tfhmagazine.com/articles/saltwater/gobiodon-histrio
- 13.LiveAquaria — Midas blennyhttps://liveaquaria.com/product/83/?pcatid=83
- 14.LiveAquaria — Tail spot blenny (retailer care sheet)https://liveaquaria.com/product/2229/tail-spot-blenny
- 15.Meerwasser-Lexikon — Ecsenius stigmaturahttps://reeflex.net/tiere/1762_Ecsenius_stigmatura.htm
- 16.LiveAquaria — Starry blenny (retailer care sheet)https://www.liveaquaria.com/products/starry-blenny
- 17.Scott W. Michael — Uber algae eaters: the lawnmower blennies (Tropical Fish Hobbyist)https://www.tfhmagazine.com/articles/saltwater/uber-algae-eaters-the-lawnmower-blennies-full-article
- 18.Jeff Kurtz — The lawnmower blenny: a funny, fascinating fish of unpredictable utility (Reef Builders, 2015)https://reefbuilders.com/2015/05/08/the-lawnmower-blenny-a-funny-fascinating-fish-of-unpredictable-utility
- 19.Meerwasser-Lexikon — Salarias fasciatushttps://reeflex.net/tiere/66_Salarias_fasciatus.htm
- 20.LiveAquaria — ProAquatix royal gramma basslet (retailer)https://www.liveaquaria.com/products/proaquatix-royal-gramma-basslet
- 21.The Biota Group — Royal gramma basslet (captive-bred, product page)https://shop.thebiotagroup.com/products/royal-gramm
- 22.Jeff Kurtz — Go ahead and buy a (captive-bred) Banggai cardinalfish (Reef Builders, 2014)https://reefbuilders.com/2014/12/17/go-ahead-and-buy-a-captive-bred-banggai-cardinalfish
- 23.Microcosm Aquarium Explorer — Green mandarinhttps://en.microcosmaquariumexplorer.com/wiki/Green_Mandarin
- 24.Bulk Reef Supply — How to care for mandarin dragonetshttps://www.bulkreefsupply.com/content/post/how-to-care-for-mandarin-dragonets
- 25.LiveAquaria — Six line wrasse (retailer care sheet)https://www.liveaquaria.com/products/six-line-wrasse
- 26.FishBase — Pseudocheilinus hexataenia, sixline wrassehttps://www.fishbase.org/summary/5617
- 27.LiveAquaria — Melanurus wrassehttps://www.liveaquaria.com/product/2285/
- 28.LiveAquaria — Yellow tang, Hawaii (retailer care sheet)https://www.liveaquaria.com/products/yellow-tang-hawaii
- 29.FishBase — Zebrasoma flavescens, yellow tanghttps://www.fishbase.se/summary/SpeciesSummary.php?id=6018
- 30.Jeff Kurtz — The kole tang: a commendable surgeonfish for medium-sized aquariums (Reef Builders, 2014)https://reefbuilders.com/2014/06/16/the-kole-tang-a-commendable-surgeonfish-for-medium-sized-aquariums
- 31.Reefs.com — Kole yellow eye tang species profilehttps://reefs.com/fish/kole-yellow-eye-tang/
- 32.Quality Marine — Yellow eye kole tang (importer listing)https://www.qualitymarine.com/quality-marine/fish/tangs/ctenochaetus/kole-yellow-eye-cc-31554/
- 33.LiveAquaria — Bristletooth tomini tanghttps://www.liveaquaria.com/products/bristletooth-tomini-tang
- 34.Quality Marine — Powder blue tanghttps://www.qualitymarine.com/quality-marine/fish/tangs/acanthurus/powder-blue-31532/
- 35.Tropical Fish Hobbyist — Paracanthurus hepatus (2020)https://tfhmagazine.com/articles/saltwater/paracanthurus-hepatus
- 36.LiveAquaria — Blue tang (retailer care sheet)https://www.liveaquaria.com/product/330/
- 37.Quality Marine — Blue hippo tang (importer listing)https://www.qualitymarine.com/quality-marine/fish/tangs/paracanthurus/blue-hippo-31506/
- 38.Meerwasser-Lexikon — Paracanthurus hepatushttps://reeflex.net/tiere/524_Paracanthurus_hepatus.htm
- 39.LiveAquaria — Foxface lo (retailer care sheet)https://liveaquaria.com/product/687/?pcatid=687
- 40.Jeff Kurtz — Foxface rabbitfish, hardy herbivore overview (Reef Builders, 2013)https://reefbuilders.com/2013/10/02/foxface-rabbitfish-siganus-vulpinus-hardy-herbivore-overview
- 41.LiveAquaria — Flame angelfish (retailer care sheet)https://www.liveaquaria.com/product/444/?pcatid=444
- 42.LiveAquaria — Coral beauty angelfishhttps://www.liveaquaria.com/product/438/?pcatid=438
- 43.LiveAquaria — Copperband butterflyfishhttps://www.liveaquaria.com/product/212/?pcatid=212
- 44.LiveAquaria — Longnose hawkfishhttps://www.liveaquaria.com/product/199/?pcatid=199
- 45.LiveAquaria — Volitan lionfishhttps://www.liveaquaria.com/product/279/
- 46.LiveAquaria — Humu Picasso triggerfishhttps://www.liveaquaria.com/product/253/?pcatid=253
- 47.LiveAquaria — Arothron dog face pufferhttps://www.liveaquaria.com/product/222/?pcatid=222
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