Royal Gramma

Gramma loreto

A hardy purple-and-gold beauty — peaceful, colourful, and nano-friendly.

Difficulty: BeginnerReef-safe community fishReef-safe

The royal gramma (Gramma loreto) is a hardy, jewel-purple-and-gold basslet from Caribbean reef caves — peaceful toward other fish, nano-friendly, and one of the easiest splashes of colour you can add. The one rule: keep just one per tank, because they scrap with their own kind.

📊 What keepers actually ask: The two things keepers ask most: “can I keep two?” (best not — they fight) and “will it eat my shrimp?” (it may bother very small ones).

Care at a glance

Adult size	Small — about 3 in (7–8 cm).
Lifespan	Around 5–7 years with good care.
Minimum tank	20–30 gallons with plenty of rockwork and caves to claim.
Temperature	75–82°F (24–28°C).
pH	8.1–8.4.
Specific gravity	1.020–1.026 (≈35 ppt; keep it stable).
Other targets	Likes caves and somewhat subdued lighting; keep nitrate low.
Diet	Carnivore — small meaty foods: frozen mysis and brine shrimp, chopped seafood. Often prefers frozen/live over dry.
Temperament	Peaceful toward other fish, but territorial toward its own kind — keep a single. May harass very small ornamental shrimp.
Reef-safe	Yes with corals — reef-safe. Not fully invert-safe: it can pick at very small shrimp.
Natural range	Caribbean reefs (Bahamas, Bermuda and the wider Caribbean), where it hangs in cave mouths.

Beginner-friendly, done right. Genuinely one of the best beginner marine fish: hardy, cheap, disease-resistant and full of colour. The only real pitfall is buying two — they fight. One royal gramma per tank and it's plain sailing.

Planning your stock list? Before you buy, run your tank and wish-list through our free stocking & tank-size calculator — it checks this fish's minimum tank and shoal size and flags any aggression clash, so you don't overstock.

The fish store gets these wrong

Common myths, kindly corrected — no shame for having believed them.

“Royal grammas and false grammas are the same.” They're not — the bicolor dottyback looks similar but is far more aggressive. Buy the real Gramma loreto.
“You can keep a group.” Only in a large, rockwork-heavy tank with all added at once — in a normal tank they fight down to one. Keep a single.

Before you buy

Buy one per tank (a simultaneous group is only for big, cave-rich systems).
Give it caves and overhangs — it's a cave-dweller.
Have small meaty frozen foods ready; it may ignore dry food at first.
Watch it around very small ornamental shrimp.

Quarantine and get help if…

We can't diagnose from a photo — but these are the signs to stop watching, quarantine, and get an aquatic vet or an experienced reefer's eyes on it:

White salt-grain spots, flashing, or rapid gill-breathing (possible ich or velvet).
Cloudy skin patches, clamped fins, or gasping at the surface.
Hiding constantly and refusing food for days, or a hollow belly.
Any new fish added without quarantine.

Never

Never keep two royal grammas in an average tank — they fight.
Never add it to an uncycled tank.
Never rely on dry food alone — offer meaty frozen foods.
Never confuse it with the aggressive bicolor dottyback.

Common royal gramma questions

Can I keep two royal grammas together?

Usually not. Royal grammas are territorial toward their own kind and will fight — often to the death — in an average tank. Keep a single, or attempt a simultaneous group only in a large, rockwork-heavy system.

Are royal grammas reef-safe?

Yes with corals — they won't bother them. They're not fully invert-safe, though; a royal gramma may harass very small ornamental shrimp.

What size tank does a royal gramma need?

About 20–30 gallons with plenty of caves and rockwork to claim. They're nano-friendly as long as there's structure to hide in.

How long do royal grammas live?

Around 5–7 years with stable water and good food.

What do royal grammas eat?

They're carnivores — feed small meaty foods like frozen mysis and brine shrimp and finely chopped seafood; they often prefer these to dry flake.

Sources & further reading

This guide was written and fact-checked against these authorities. It's honest, general guidance — not a diagnosis, and not a substitute for an aquatic vet or your own test kit:

Saltwater Aquarium Blog — Royal Gramma Care Guide — adult size, tank size, water, diet, temperament, reef-safe, natural range
LiveAquaria — Royal Gramma Basslet — lifespan (5–7 years), care level, invert caution

Written and fact-checked by The Coralkin Team against marine-aquarist and veterinary sources — if your royal gramma shows a red-flag sign above, quarantine and get an aquatic vet or an experienced reefer's eyes on it. We never guess a care number.

🔬 Review status: team-written and fact-checked against cited sources · not yet reviewed by a marine vet. How we research & fact-check →

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