At a glance the quick version
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.23
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.21
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.31
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.23
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.123
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
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 2022)1
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Yellow Assessor. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- 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
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at [email protected] and we will fix it.
- 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.