Allen’s Damsel

Allen’s Damsel (Pomacentrus alleni), also called the Andaman Damselfish, is a small neon-blue damselfish with a yellow anal fin and a dark streak along the lower tail. It’s a reef compatible choice for marine aquariums when you want a compact fish that stays active around rockwork.

What You’ll Observe:

• Patrols open water in short loops, then darts back to a favorite crevice
• Picks a “home base” in the rockwork and returns to it throughout the day
• Comes out quickly at feeding time and stays visible once it learns your routine
• May shift small amounts of sand near rock edges while exploring and grazing surfaces

Provide plenty of rockwork with multiple holes so it can choose a shelter and still cruise open areas. Offer a mixed diet of small meaty foods plus algae-based flakes/pellets 1–2 times daily, and keep your rockwork secure so any light digging doesn’t undermine it. With consistent feeding and a stable layout, it settles into a predictable daily pattern.

Why does an Allen’s Damsel sometimes look gray instead of electric blue?
Temporary color dulling is common during shipping, quarantine, or the first days in a new tank. As it settles into a territory and begins eating confidently, the stronger blue coloration typically returns.

Is it normal for this damsel to stay in one cave (or a PVC pipe) at first?
Yes—many individuals “anchor” to one shelter early on and make short scouting trips from it. Once it recognizes the tank as stable and learns feeding times, you’ll usually see longer, more frequent laps.

Can I keep Allen’s Damsels as a pair or a small group?
Often, yes—adding them at the same time helps them sort out spacing more smoothly. A tank with multiple hiding spots lets each fish adopt its own preferred retreat while still sharing the open areas.

Will it dig or move sand around my rockwork?
It can, especially when it’s choosing a sleeping spot or tuning up its preferred nook. If your aquascape is stable and supported well, this is usually just a minor, localized behavior.

Any tips for catching an Allen’s Damsel later without tearing down the reef?
A fish trap baited with the foods it already rushes to works well, especially if you feed lightly for a day beforehand. Many hobbyists also have success by placing the trap near its regular “home base” and giving it time to enter on its own schedule.

Each fish is checked for strong appetite and activity before we approve it for your tank.