Red Spot Glass Cardinal (Apogon parvulus) is a peaceful schooling fish known for its translucent body, silver stripe, and bright red tail spot. Many aquarists look for a species that stays small, avoids aggression, and fits safely in reef tanks, and this fish meets those needs when provided with stable water conditions. Customers also appreciate that it settles quickly when kept in groups and fed consistently. Trust in careful handling and reliable health standards helps ensure confidence when choosing a delicate marine fish like the Red Spot Glass Cardinal.

Appearance

The Red Spot Glass Cardinal has a translucent body marked by a black and silver horizontal stripe. A red spot sits at the base of the tail and becomes more pronounced as the fish matures. The species stays small and shows little visual difference between males and females.

Care & Requirements

A group of five or more helps reduce stress and encourage consistent schooling. A 30 gallon tank supports a small group when the environment includes rockwork for cover and calm areas for resting. Dim or blue lighting helps them settle faster, especially during the first week. They are slow swimmers and benefit from two to three small feedings per day using mysis shrimp, enriched brine, copepods, or finely chopped krill. Target feeding prevents food loss to faster species. Transport sensitivity is common, so slow acclimation and stable water quality are important.

How often should I feed the Red Spot Glass Cardinal?
Two to three small feedings each day maintain steady energy levels.

Why do some Red Spot Glass Cardinals struggle after shipping?
They are sensitive to handling stress, so careful acclimation and low lighting help them recover.

Is dim lighting required for this species?
Dim or blue-spectrum lighting supports settling during the first few days.

Behavior

This species becomes more active in low light and stays close to cover when startled. Schooling behavior reduces stress, and stable conditions encourage steady swimming. They avoid confrontation and do not disturb coral or invertebrates.

Tank Mates & Compatibility

These fish work well with peaceful reef species that will not chase or outcompete slow feeders. Small gobies, peaceful wrasses, and other calm cardinalfish are good choices. Avoid fast or territorial species that may interrupt feeding.

Can they be kept with larger peaceful fish?
Yes, as long as feeding competition is low.

Do they get along with shrimp and other invertebrates?
Yes, they are fully reef safe.

Can I mix them with other cardinalfish species?
Yes, when space allows and the other species are peaceful.

Aquaculture/Availability

Currently, captive-bred Red Spot Glass Cardinals are not widely available, and most offerings are wild-caught. Availability varies due to limited collection periods and their sensitivity to transport.

Are captive-bred Red Spot Glass Cardinals ever offered?
They appear occasionally but are uncommon.

Why are they often out of stock?
Collection periods are limited, and shipping success controls supply.

Do wild-caught individuals adapt well to aquarium food?
Yes, once settled, they accept enriched frozen foods.

FAQ

How many Red Spot Glass Cardinals should be kept in one tank?
A group of five to seven supports natural schooling and reduces stress. Smaller groups hide more and may feed inconsistently.

What is the best way to acclimate a Red Spot Glass Cardinal after shipping?
Slow drip acclimation helps them adjust to temperature and salinity changes. Keep lights dim and provide cover to reduce stress.

Can the Red Spot Glass Cardinal be kept in nano reef tanks?
A stable 30-gallon system supports a small group when filtration and feeding routines are reliable.

What water flow level do Red Spot Glass Cardinals prefer?
Moderate or sheltered flow zones let them rest and feed without difficulty.

How long does it take for a new group to settle in?
Most groups adjust within one to two weeks when tank mates are peaceful and lighting is subdued.

Do Red Spot Glass Cardinals jump?
They may jump when startled, so secure lids are recommended.

Are they compatible with corals and reef invertebrates?
Yes, they do not nip coral tissue or bother invertebrates.

What signs of stress should I watch for?
Rapid breathing, isolated swimming, and refusal to feed indicate acclimation issues or water quality instability.