Red Soapfish

Suttonia lineata, commonly known as the Red Soapfish, is a small, cryptic soapfish with an understated but highly distinctive appearance. Live specimens are typically dark red to reddish-brown with irregular darker mottling, while the lower portion of the head becomes noticeably paler. Its elongated body, secretive behavior, and tendency to remain close to coral and rockwork give it a fascinating presence for aquarists interested in unusual reef-associated marine fish.

Native to the Indo-Pacific, Suttonia lineata is a reef-associated species found from shallow water down to roughly 200 feet. It is strongly benthic and cryptic, spending much of its time concealed within coral structure, crevices, and shaded areas rather than swimming prominently in open water. Adults remain small, reaching approximately 3.2 inches.

Because this species is naturally secretive and not commonly maintained compared with more familiar reef fish, it is best suited to an established aquarium with peaceful tankmates, abundant shelter, and an aquarist prepared to accommodate its carnivorous feeding behavior. Its small adult size makes it suitable for relatively compact marine systems, provided the aquarium is mature and thoughtfully aquascaped.

Quick Care Guide

Care Level: Moderate
Minimum Tank Size: 20 gallons
Temperament: Peaceful / Predatory
Diet: Carnivore
Reef Safe: With Caution
Region: Indo-Pacific
Scientific Name: Suttonia lineata

Tank Requirements

Provide an established saltwater aquarium with extensive rockwork containing narrow caves, overhangs, crevices, and shaded retreats. This species naturally remains close to reef structure and should always have several secure places where it can completely withdraw from view.

A densely structured aquascape is more important than extensive open swimming space. Live rock is particularly useful because it provides both shelter and opportunities to encounter small natural prey.

Moderate water movement is appropriate, but sheltered low-flow areas should be available around caves and feeding locations. A secure aquarium cover is recommended, particularly during acclimation.

Diet and Feeding

Suttonia lineata is a small carnivorous predator that should be offered appropriately sized meaty marine foods.

Suitable foods include enriched mysis shrimp, finely chopped shrimp, small pieces of krill, enriched brine shrimp, copepods, finely chopped clam, and quality frozen carnivore blends. Small marine pellets may eventually be accepted by established individuals.

Because of its cryptic behavior, food may need to be delivered close to its preferred hiding area, especially during acclimation. Small feedings once or twice daily are appropriate. Feeding after the aquarium lighting has dimmed may also help shy individuals begin eating.

Temperament and Tankmates

The Red Soapfish is generally secretive and non-aggressive toward fish too large to be considered prey. It is better suited to calm community aquariums than systems containing highly aggressive or constantly active tankmates.

Choose peaceful fish that will not occupy every cave or aggressively dominate feeding. Small gobies, tiny crustaceans, and other animals capable of fitting into its mouth may potentially be viewed as prey.

Avoid aggressive triggerfish, large wrasses, territorial dottybacks, and other species likely to intimidate a small, reclusive fish or prevent it from feeding.

Reef Compatibility

Suttonia lineata is best considered reef safe with caution.

It is not known for consuming coral tissue and is naturally associated with coral reef habitats. However, as a small carnivorous predator, it may consume tiny shrimp, crustaceans, and other suitably sized mobile invertebrates.

Established corals and larger reef invertebrates are generally a much lower concern than very small crustaceans and tiny fish.

Water Parameters

Temperature: 75–80°F
Specific Gravity: 1.024–1.026
pH: 8.1–8.4
Alkalinity: 8–12 dKH

Maintain stable water conditions with good oxygenation and consistent salinity. Because cryptic reef species can be sensitive during acclimation, avoiding abrupt changes in temperature and water chemistry is especially important.

Common Considerations

• Very secretive behavior: Expect the fish to spend considerable time hidden within rockwork, particularly after introduction.
• Small adult size: Adults reach only about 3.2 inches, but abundant shelter remains essential.
• Predatory feeding: Tiny shrimp, crustaceans, and very small fish may potentially be consumed.
• Target feeding may help: Newly introduced specimens may require food placed close to their preferred cave or retreat.
• Peaceful surroundings preferred: Avoid aggressive or excessively competitive tankmates that could prevent this cryptic species from feeding normally.