TankBud

Threadfin cardinalfish

Zoramia leptacantha

Also known as Longspine Cardinalfish, Threadfin Cardinal

SaltwaterFish

Threadfin cardinalfish (Zoramia leptacantha)
Haplochromis · Public domain

Care at a glance

Temperature
72–79°F
22–26°C
pH
8.1–8.4
Adult size
2.4 in
6 cm
Minimum tank
30 gal
114 L
Temperament
Peaceful
Social behavior
Shoaling
Swim level
Middle
Diet
Carnivore
Difficulty
Medium
Breeding
Mouthbrooder · Medium
Rarity
Common
Reef safe
Reef safe
Family
Apogonidae
Origin
Indo-Pacific reefs, from the Red Sea to Samoa and Tonga

Overview

The threadfin cardinalfish is a small, peaceful schooling cardinalfish for the middle of a calm reef tank. It is a step up from the easiest marine fish.

Did you know

The threadfin cardinalfish's nearly transparent body helps it vanish into open water as it schools over reef flats by day. Most cardinalfish rely on darkness and cave cover instead. That makes it one of the few truly diurnal schooling cardinalfish in the trade.

Caring for the threadfin cardinalfish

Keep threadfin cardinalfish in a school of five or more, in at least 30 gal (114 L). Give them gentle flow, subdued lighting and plenty of coral branches or urchin spines to gather around. A proper school feels secure enough to hover out in the open instead of hiding.

Hold the water at 72 to 79°F (22 to 26°C) and a pH of 8.1 to 8.4. Feed a varied diet of brine shrimp, mysis and other finely chopped meaty foods several times a day. Frequent meals let the slower fish in the group get their share.

The threadfin cardinalfish is shy and docile, and faster fish can intimidate it away from food. Keep it with calm eaters and no boisterous competitors. It is reef safe with corals and invertebrates.

Monogamous pairs form within the school, and the male carries the fertilized eggs in his mouth through incubation. Breeding them is moderately hard.

Good to know

The threadfin cardinalfish, Zoramia leptacantha, is a cardinalfish in the family Apogonidae. It is also sold as the longspine cardinalfish or the threadfin cardinal.

In the wild

The threadfin cardinalfish ranges across the Indo-Pacific, from the Red Sea and Mozambique to Samoa and Tonga. Its range runs north to the Ryukyu Islands and south to New Caledonia. It forms dense, mixed-species aggregations in sheltered lagoons and bays, at depths of about 1 to 12 meters.

Weekly picks

Tank mates

The threadfin cardinalfish is a peaceful, shoaling species that keeps to the middle. These picks share a community profile with it, are safe together in both directions, and overlap on water type, temperature and pH.

Check the full mix in the stocking calculator

Common questions

What size tank does a threadfin cardinalfish need?

A threadfin cardinalfish needs at least 30 gal (114 L). It spends most of its time in the middle.

What temperature and pH does a threadfin cardinalfish need?

A threadfin cardinalfish is comfortable at 72–79°F (22–26°C) with a pH of 8.1–8.4.

What does a threadfin cardinalfish eat?

A threadfin cardinalfish eats brine shrimp, mysis and other finely chopped meaty foods. Feed it several times a day so the slower fish in the group get their share.

How big does a threadfin cardinalfish get?

An adult threadfin cardinalfish reaches about 2.4 in (6 cm).

Does a threadfin cardinalfish need a group?

Yes. A threadfin cardinalfish is a shoaling species and should be kept in a group, not singly.

How does a threadfin cardinalfish breed?

Threadfin cardinalfish form monogamous pairs within the school, and the male carries the fertilized eggs in his mouth. Breeding them is moderately hard.

Related species