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Half-Lined Cardinalfish (Apogon semilineatus)

Find Half-Lined Cardinalfish across reef-livestock retailers on ReefDock. Compare sources, check known pricing where available, and review care information before you buy.

Half-Lined Cardinalfish
Photo: Totti · CC BY-SA 4.0
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Where to buy Half-Lined Cardinalfish

ReefDock searches the following reef retailers for this fish. Click through to see the live price.

  • Saltwaterfish

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  • Amazon

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  • Petco

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About Half-Lined Cardinalfish

The Half-Lined Cardinalfish is a small, slender fish with a reddish-orange body and distinctive dark stripe running laterally along the head and anterior body. Two prominent dark eye-like spots (ocelli) on the dorsal fin base are characteristic. The fish has a somewhat elongated, compressed body typical of the cardinalfish family.

Key facts

Appearance
The Half-Lined Cardinalfish is a small, slender fish with a reddish-orange body and distinctive dark stripe running laterally along the head and anterior body. Two prominent dark eye-like spots (ocelli) on the dorsal fin base are characteristic. The fish has a somewhat elongated, compressed body typical of the cardinalfish family.
Temperament
Peaceful
Reef safety
Reef Safe
Min tank size
20 gallons
Family
Apogonidae
Water Parameters
Temperature: 72-82°F pH: 8.1-8.4 Salinity: 1.02-1.025
Feeding Schedule
2-3 times daily
Care Requirements
• Minimum 20 gallon tank with low to moderate flow and shaded areas or caves for daytime refuge • Temperature 72–82°F, pH 8.1–8.4, salinity 1.020–1.025 • Nocturnal; does not require intense lighting but benefits from dimmer acclimation periods • Feed 2–3 times daily with small meaty foods (mysis shrimp, small fish pieces) • Peaceful but may eat very small crustaceans; otherwise safe for most reef inhabitants
Difficulty Level
Moderately difficult. While hardy once acclimated, these nocturnal fish are sensitive to strong water flow and sudden changes in lighting. They require stable conditions and may be outcompeted for food by more aggressive species.
Care Level
Moderate
Origin
Indo-Pacific region, including the Red Sea, East Africa, and extending to the Philippines and Indonesia.
Diet Details
Feed small meaty foods including mysis shrimp, brine shrimp, and finely chopped fish flesh. May accept small prepared carnivore pellets. Feed 2–3 times daily with small portions, as cardinalfish are nocturnal and feed at night but will accept daytime offerings in established tanks.

Research before you buy

ReefDock is the sister app to Reef Trak. Use Reef Trak to research and log fish, keep tank parameters organized, and maintain a complete livestock history. Log this fish on Reef Trak.

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