Bartlett's Anthias Care Guide: The Ultimate Reef-Safe Schooling Fish

Species Overview#

Bartlett's Anthias (Pseudanthias bartlettorum) is the gateway Anthias for reef hobbyists who want the schooling spectacle without the brutal mortality rate that follows species like Ventralis or Square Anthias home from the LFS. A small, sunset-colored fish from the Marshall Islands, it hovers in mid-water, picks zooplankton out of the current, and — when kept in a proper harem — turns the upper third of a reef tank into living art. The males flush violet and yellow during display; the females stay a softer peach-pink. In a school of six, the contrast is the entire reason you bought the fish.

What separates Bartlett's from the rest of the Anthiinae subfamily is metabolic stamina. They eat constantly because they evolved to feed on drifting plankton all day, but unlike their fussier cousins they will accept prepared foods within a few days of arrival, and they tolerate the warmer, brighter conditions of a typical mixed reef. They are not, however, beginner fish. Get the harem ratio wrong, skip an automatic feeder, or skimp on quarantine, and you will lose the entire group inside a month.

Adult size

3.5 in (9 cm)

Lifespan

4-7 years

Min tank

75 gallons (harem)

Temperament

Peaceful, harem-forming

Difficulty

Intermediate-Advanced

Diet

Zooplanktivore

Origin: The Marshall Islands and Palau#

In the wild, Pseudanthias bartlettorum is a Western Pacific fish, with populations concentrated around the Marshall Islands, the Gilbert Islands, and Palau. They live on the upper reef slope at depths of 15 to 50 feet, where strong tidal currents push clouds of zooplankton across the reef edge. They form mixed-sex aggregations of dozens to hundreds, hovering a few feet off the bottom and darting back to crevices when a predator passes overhead.

That habitat profile dictates almost every choice you will make in your tank. They want consistent flow, structure to retreat into, mid-water swimming room, and a constant trickle of small, drifting food. Tanks that nail those four variables produce healthy harems that spawn regularly. Tanks that miss them produce stressed fish that fade and disappear one by one.

Sexual Dimorphism: Identifying Males vs. Females#

Females are the default. Both sexes show a pink-to-orange body with a yellow dorsal flush, but females are smaller (around 2.5 inches), more uniformly peach, and lack the elongated dorsal fin filament that develops in mature males. Males grow to the full 3.5-inch maximum, develop a deeper magenta tone along the flanks, and sport a noticeably extended third dorsal spine that they flick during courtship displays.

Bartlett's are protogynous hermaphrodites, meaning every fish is born female. If the dominant male dies or is removed, the largest and most behaviorally dominant female in the group will begin transitioning to male within days. Color changes appear within two to three weeks; full anatomical conversion takes a couple of months. This is why losing a male in an established harem rarely collapses the school — the system self-corrects, provided the remaining females are healthy.

Lifespan and Maximum Size (3.5 inches)#

A well-kept Bartlett's Anthias reaches 3.5 inches at maturity and lives 4 to 7 years in captivity. Wild specimens have been documented at over a decade, but captive lifespans are throttled by two recurring problems: chronic underfeeding (the fish slowly starves on once-daily meals) and unresolved parasitic infections from skipped quarantine. Eliminate both, and a harem can outlast most of your other reef stock.

Water Parameters & Tank Requirements#

This is a current-loving, mid-water fish from a high-energy reef environment. Replicating that environment is more important than chasing perfect numbers on a test kit. Stable parameters in the right range beat unstable parameters at the textbook ideal.

Minimum Tank Size (75+ gallons for a harem)#

A single Bartlett's male could survive in a 30-gallon nano, but it will pace the glass and look miserable. The species is built for groups, and a proper harem of one male plus three to five females needs a 75-gallon tank at the absolute minimum. A 90 to 125-gallon mixed reef is the sweet spot — enough horizontal swimming room for the school to spread out, enough volume to buffer the heavy feeding schedule, and enough rockwork for subdominant females to retreat from the male during the most intense courtship periods.

Footprint matters more than gallons. A 75-gallon tank that is 48 inches long beats a 75-gallon cube every time. Anthias swim laterally across the upper reef slope; they need length, not depth.

Flow and Oxygenation: Recreating the Reef Slope#

Aim for total tank turnover of 30 to 50 times per hour, distributed so that the upper half of the tank shows visible, varied current. A pair of gyre pumps or two opposing powerheads on a wave controller produce the chaotic flow patterns Anthias evolved with. They want to swim against current, not in dead water.

High flow also drives oxygenation, which matters because Anthias have an oxygen demand well above most reef fish. A protein skimmer rated for double your tank volume, plus a sump with a refugium, will keep dissolved oxygen high enough to support a six-fish harem. If you see your harem yawning frequently or hovering near the surface, your oxygen is too low — increase surface agitation immediately.

Specific Parameters: 72-78°F, pH 8.1-8.4, dKH 8-12#

Target tropical reef parameters with no surprises:

For a deeper treatment of saltwater chemistry, the saltwater aquarium guide covers parameter testing cadence and dosing regimes.

Diet & Feeding#

Feeding is the single most common failure point for Anthias keepers. Treat this fish like a freshwater tetra and it will starve in slow motion over six to eight weeks. The pinched-belly look you sometimes see at the LFS is almost always a feeding problem, not a disease.

High Metabolism: The "Multiple Feedings" Requirement#

Bartlett's Anthias evolved to graze on plankton continuously throughout daylight hours. In a home tank, that translates to a minimum of three feedings per day, with five being ideal for the first six months while the harem establishes weight. Each feeding should be small enough to be consumed within 60 seconds — no leftover food drifting into the rocks.

If your work schedule will not accommodate three feedings, you have two options: a reliable automatic feeder, or a different species. There is no third option.

Best Foods: Mysis, Vitamin-enriched Brine, and Cyclops#

Build the diet around small, meaty marine foods. Frozen mysis shrimp is the staple — thaw a cube in tank water, vitamin-enrich it with a Selcon-style supplement once daily, and target-feed if necessary. Rotate in vitamin-enriched frozen brine, frozen cyclops, and live or frozen copepods. Live Tigriopus (tig pods) added to a refugium will trickle continuously into the display and provide the kind of pursuit feeding Anthias love.

For reef tanks with a working refugium, a self-sustaining population of benthic copepods and amphipods supplies a low-level but constant background food source. It will not replace scheduled feedings, but it bridges the long gaps between them and dramatically improves coloration.

Training to Eat High-Quality Pellets#

Most aquacultured and well-conditioned wild Bartlett's will accept small high-quality pellets within two weeks if introduced patiently. Start with a sinking pellet in the 0.5 to 1.0 mm range, soaked briefly in tank water and a vitamin supplement so the pellet sinks slowly through the water column where Anthias prefer to feed. Pellets are not a replacement for frozen food, but they are an excellent backstop for a sitter or for travel days.

Tank Mates & Compatibility#

This is one of the most reef-safe and most peaceful fish in the saltwater hobby — provided you respect the harem dynamic and pick neighbors that will not bully a mid-water column dweller.

The Harem Dynamic: One Male, Multiple Females#

The non-negotiable rule: one male per group. Two males in any tank under 300 gallons will fight, and the loser will be hounded into starvation within days. The standard captive harem is one male and three to five females; six females is the practical maximum before social aggression starts to creep up.

If you cannot reliably sex your purchase, buy a group of five small juveniles (all functionally female) and let the largest naturally transition to male over the following months. This is the safest path for hobbyists buying online sight unseen.

Reef Safety: Interaction with Corals and Inverts#

Bartlett's Anthias are completely reef-safe. They will not nip LPS, SPS, soft corals, or zoanthids. They will not touch ornamental shrimp, hermit crabs, snails, or feather dusters. The only theoretical concern is the occasional curious peck at a freshly hatched amphipod or copepod, which is exactly the behavior you want — they help control pod populations without damaging livestock you actually care about.

Their plankton-grazing behavior actually benefits SPS-dominant tanks: they pick up food particles drifting past corals and turn them into nutrient-rich waste that broadcasts back into the system through your skimmer and refugium.

Suitable Neighbors: Blennies, Tangs, and Fairy Wrasses#

Pair Bartlett's with peaceful or semi-aggressive reef fish that occupy different parts of the water column. Excellent matches include the tomini tang, the yellow tang, the kole tang, the lawnmower blenny, the tailspot blenny, and most fairy or flasher wrasses like the mccoskers flasher wrasse and the melanurus wrasse. A pair of ocellaris clownfish or a single royal gramma rounds out a peaceful reef community without crowding the Anthias' mid-water territory.

Avoid territorial bottom fish that claim the upper rockwork (most dottybacks except the orchid dottyback used carefully), large angelfish that bully smaller schoolers, and any aggressive triggerfish. Other Anthias species can work in very large tanks (180+ gallons) but expect competition for the male role and prepare to remove a fish if a second male emerges from a mixed group.

For a broader compatibility framework, the saltwater fish guide covers stocking density and behavioral grouping for typical reef builds.

Common Health Issues#

The species is hardy by Anthias standards, which means the diseases you need to worry about are the ones every saltwater fish faces — but the consequences hit harder because Anthias are sensitive to stress and fast-moving when symptomatic.

Sensitivity to Shipping Stress#

Bartlett's Anthias are wild-caught from deep reef edges, then bagged and shipped through a chain of transshipment points before they reach your LFS. The single biggest mortality event in this species' captive life is the first 72 hours after arrival. Decompression issues from improper collection, prolonged ammonia exposure in shipping bags, and temperature swings all stack up.

Drip acclimate slowly over 60 to 90 minutes, keep the lights off in the destination tank for the first 24 hours, and resist the urge to feed for the first 12 hours so the fish can settle. The how to acclimate fish guide walks through the temperature and salinity equalization steps that minimize osmotic shock for sensitive species like this one.

Identifying Uronema and Marine Ich#

The two parasites you will see in this species are Cryptocaryon irritans (marine ich) and Uronema marinum. Marine ich appears as discrete white salt-grain spots on the fins and body, with the fish flashing against rockwork and breathing rapidly. It is treatable with copper or tank transfer methodology in a quarantine tank. Reef tanks cannot be treated with copper — you will need to remove the fish.

Uronema is the more dangerous of the two. It presents as red ulcers, raw patches, or sudden fin erosion, often progressing to death within 48 to 72 hours. It thrives in tanks with elevated nitrate and dissolved organics, which is exactly the environment heavy-feeding Anthias create if husbandry slips. Formalin baths and elevated water quality are the standard intervention, but prevention beats treatment — keep nitrates under 10 ppm and skim aggressively.

The Importance of a Quiet Quarantine Tank#

Every Bartlett's Anthias should spend at least 30 days in a quarantine tank before entering the display. Use a bare-bottom 20 to 40-gallon tank with PVC fittings for cover, sponge filtration, and dim lighting. Treat prophylactically with copper at therapeutic dose for the full 30 days, then observe for at least another week without copper before transfer.

Where to Buy & What to Look For#

This is where the Unique angle for Bartlett's matters most. The visual cues you can pick up at a local fish store will save you from a dead-on-arrival fish that no amount of good husbandry can rescue.

Sourcing from Local Fish Stores (LFS) vs. Online#

A reputable LFS that holds Anthias for at least seven days before sale is the gold standard. You get to see the fish eating, you can pick your specific individual from the group, and you have recourse if it dies in the first 14 days. Online vendors offer wider selection and often better pricing, but you give up the chance to inspect the fish in person and you pay shipping risk on a species that does not love being shipped twice.

If you go online, choose vendors that clearly label collection origin (Marshall Islands stock tends to ship better than Indonesian) and that offer overnight shipping with a solid guarantee. Avoid any vendor that ships standard ground or two-day to your zone.

Signs of a Healthy Individual: Active Swimming and Coloration#

A healthy Bartlett's at the store should be:

A second check worth doing: ask the LFS owner when the fish arrived. Anthias that have been in the store for less than 72 hours have not had time to recover from shipping stress; ones that have been there for ten or more days, eating prepared foods daily, are vastly more likely to survive the transition to your tank.

Quick-Reference Cheat Sheet#

Bartlett's Anthias rewards hobbyists who respect the species' two non-negotiables: feed them like a plankton stream and stock them as a proper harem. Get those right, quarantine them properly, and pick healthy individuals from a reputable source, and you will end up with one of the most visually striking and behaviorally interesting schools in the saltwater hobby. The fish has a deserved reputation as the easiest Anthias to keep — but "easiest" still means you cannot cut corners on feeding cadence or harem composition.