Not furry, but we like them anyway.

Yellow Assessor

Assessor flavissimus

Also called Gold assessor basslet, Yellow devilfish, Yellow scissortail, Golden mini grouper

SpeciesShort profile

From Western Central Pacific: the Great Barrier Reef and Papua New Guinea1 2

At a glance the quick version

Length5.5 to 7.6 cm1 2 3

Sizesmall

Glowing golden colour

Peaceful and reef safe

Charming habit of swimming upside down

3 2

Looks how to spot one

Elongated, compressed body with a forked tail

A slim, bright golden-yellow fish with a reddish-orange stripe from the eye to the gill cover and reddish-orange edging on the dorsal and anal fins.2 3

Coloursyellowgoldreddish-orange edging2 3

Personality what they are like

Peaceful and a little reserved. It gets on with other species and leaves invertebrates alone, though males can be territorial toward each other.3

Daily activity how busy a day looks

Spends much of its time near caves and ledges, often hanging upside down under overhangs.2 1

Grooming and care the hands-on bits

Provide plenty of rock caves and overhangs and feed small meaty foods about twice a day.3

Home where they are happiest

Minimum about 30 US gallons (114 L) for one fish, more for several, with lots of rock caves. Saltwater at about 22 to 26 °C (72 to 78 °F), pH 8.1 to 8.4, dKH 8 to 12, specific gravity 1.020 to 1.025. FishBase gives a natural range of about 27 to 30 °C.3 1

Food basics what goes in the bowl

Carnivore. Wild fish eat plankton; in the aquarium offer finely chopped marine fish and squid, mysis shrimp and similar meaty foods.2 3

Company who they like around

Wild fish gather in small groups in caves. In home aquariums a single fish is the usual choice, since males may quarrel.1 2 3

The story where it all began

Gerald Allen and Rudie Kuiter described the species in 1976. Its species name comes from the Latin for 'most yellow', a nod to its colour.2

Fun facts for the dinner table

1
It often swims upside down, using the ceiling of a cave or ledge as its 'floor'.1
2
Fathers carry the egg mass in their mouths until it hatches.1
3
Its scientific name flavissimus means 'very yellow' in Latin.2
4
It has been bred successfully in aquariums.1

Recognised by the official bits

IUCN Red List: Least Concern (assessed 2022)1

The care rhythm a typical week and year

A typical home-care rhythm for a Yellow Assessor. A starting point, not a vet's advice.

FeedingSmall amounts once or twice a dayevery day
Temperature checkevery day
Salinity checkevery week
Top-upTop up evaporation with fresh RO water, not salt waterevery day
Water testevery week
Water changeAbout 10 to 20% of the waterevery 2 weeks
Glass cleanevery week

Owner questions the things everyone asks

How often should I feed my Yellow Assessor?

Feed small meaty foods about twice a day. Furry Diary's starting plan suggests small amounts once or twice daily. Adjust based on your fish's appetite and always check with a vet if unsure.3 Pet Wiki plan

What does a Yellow Assessor eat, and what should it never eat?

It is a carnivore that enjoys finely chopped marine fish, squid, and mysis shrimp. Never feed it plant-based foods or anything not meant for marine carnivores. For specific amounts, follow the food label and ask your vet.2 3

How much space does a Yellow Assessor need?

A minimum of about 30 US gallons (114 L) for one fish, with plenty of rock caves and overhangs. More space is needed if you keep several fish. A good breeder can help you plan the tank size.3 1

What temperature, light or water does a Yellow Assessor need?

Keep saltwater at 22 to 26 °C (72 to 78 °F), pH 8.1 to 8.4, dKH 8 to 12, and specific gravity 1.020 to 1.025. Provide moderate lighting and lots of rock caves. Furry Diary's plan includes daily temperature checks and weekly salinity checks.3 1 Pet Wiki plan

How often should I clean a Yellow Assessor's home?

Furry Diary's starting plan suggests a weekly glass cleaning and a 10-20% water change every two weeks. Also test water weekly and top up evaporation daily with fresh RO water. Always ask your vet for a schedule tailored to your tank. Pet Wiki plan

Can a Yellow Assessor live with others?

Yes, it is peaceful with other species and leaves invertebrates alone. However, males can be territorial toward each other, so a single fish is usually best. A good breeder can advise on tank mates.3 1 2

How long does a Yellow Assessor live?

Lifespan varies with care and environment. For specific information, ask your vet or a good breeder who knows the fish's history.

Can I handle a Yellow Assessor?

Handling is not recommended as it can stress the fish and damage its delicate slime coat. Enjoy watching it swim near caves and ledges instead. Always use a soft net if you must move it.2 1

Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Pet Wiki's own starting care plan. A friendly guide, not a vet's advice.

Royal Gramma

Where this comes from

Every fact on this page has a numbered source. Spotted an error? support@petwiki.app.

FishBase: Assessor flavissimus summary fishbase.seused for origin, size, habitat, behaviour, reproduction, temperature, IUCN
Wikipedia: Assessor flavissimus en.wikipedia.orgused for history, etymology, colour, size, behaviour
LiveAquaria: Gold Assessor Basslet liveaquaria.comused for care, water parameters, tank size, diet, temperament

Checked 2026-09-30. Text is written in our own words from these sources.