Arabian demoiselle

Where they come from

Arabian demoiselles hang out in the western Indian Ocean, especially the Arabian/Persian Gulf, Gulf of Oman, and down toward Pakistan and western India. You often see them schooling over reefs, jetties, and rubble in fairly warm, sometimes slightly murky water. They like structure and a bit of current to sit in while they pick food from the flow.

Setting up their tank

They are small but active. One does fine in a 20 gallon, but if you want a group, go 40 gallons or larger with lots of rockwork. Think open swimming lanes with rocky pillars and caves to break line of sight. They are good jumpers when startled, so use a tight lid or mesh screen.

• Tank size: single 20+ gal, group 40+ gal
• Temp: 75-81 F (24-27 C)
• Salinity: 1.024-1.026
• pH: 8.0-8.4
• Flow: moderate with some higher-flow areas
• Lighting: not picky; standard reef lighting is fine
• Nitrate: try to keep under ~25 ppm

They are reef safe and do well in mixed-reef setups. Use a few scattered flat rocks or tiles they can use later as nest sites if breeding happens. Keep some open water; they spend time midwater, not buried in the rock.

What to feed them

They are planktivores at heart, so think small meaty foods with a bit of variety. They learn pellets quickly and are not picky once settled.

• Daily staples: 0.5-1 mm marine pellets, quality marine flakes
• Frozen: mysis, enriched brine, copepods/calanus, finely chopped shrimp or clam
• Veggie boost 1-2x/week: spirulina pellets or a tiny pinch of nori
• Vitamins: soak food in a vitamin/omega supplement a few times a week for color and immunity

Feed small amounts 2-3 times a day if you can. They are quick, so spread the food in different spots so slower fish get some too.

How they behave and who they get along with

Compared to many damsels, Arabian demoiselles are pretty mellow, but they are still damselfish. Expect some chasing, especially at feeding time or near a favorite rock. In a small tank, keep a single fish. In bigger tanks, a small group works if you give them space and cover.

• Good tankmates: clownfish, cardinalfish, small wrasses (fairy/flashers), gobies, blennies, firefish, tangs in larger tanks, reef-safe inverts
• Use caution: dottybacks, aggressive clowns, other damsels, large hawkfish
• Skip: triggers, large predatory wrasses, groupers, anything that likes to swallow bite-size fish

Breeding tips

They are substrate spawners. A male will clean a spot on rock or a shell, the female lays eggs, and the male guards and fans them. If you keep a small group, a pair may form naturally once they mature.

• Encourage pairing: keep 4-6 juveniles in a larger tank and let them sort it out
• Nest sites: smooth rock, ceramic tile, or a scallop shell near moderate flow
• Conditions: steady warmth around 78-80 F, lots of small, high-quality meals
• Spawning sign: male intensifies color slightly, cleans and fans a patch of rock

Raising the young is the tricky part. Eggs hatch at night and the larvae are tiny and pelagic. You will need a separate larval tank, rotifers with greenwater, gentle aeration, and then newly hatched brine shrimp after a few days. If you have raised clownfish before, it is a similar routine.

Common problems to watch for

• Territorial spats: in small tanks a dominant fish may bully the rest. Add hiding spots or rehome extras.
• Parasites after import: ich or velvet show up as scratching, spots, or rapid breathing. Quarantine and treat early.
• Nutritional gaps: a flake-only diet leads to washed-out color and fin nips that heal slowly. Mix in frozen and vitamin-soaked foods.
• Jumping: startled fish can clear a gap. Use a lid.
• Nitrates creeping up: they eat often, so export nutrients with water changes, a skimmer, or macroalgae.