Matted Filefish (Acreichthys tomentosus) Breeding Guide

How the captive-bred matted filefish Acreichthys tomentosus is bred: pairing, demersal eggs on substrate, and direct-settling larvae with no pelagic dispersal phase.

Overview

Acreichthys tomentosus is an oviparous filefish that is now produced commercially in captivity; Reef Builders reports that captive-bred specimens are offered by aquaculture operations such as Biota in Palau. It is a demersal egg-layer that deposits eggs on exposed substrate, and notably it lacks a true open-ocean pelagic larval phase, settling instead onto seagrass and floating algae, which makes it one of the more rearable marine fishes.

Sexing

The sexes are not separated by obvious colour, but maturity is size-linked: females begin developing eggs (oocytes) at around 4.5 cm and carry fully formed eggs from about 8 cm onward. The practical approach is to grow on a small group to maturity and allow a compatible pair to settle, then condition that pair for spawning.

Conditioning

As an omnivore the species takes a wide diet in the wild, including amphipods, polychaetes and molluscs, and famously Aiptasia anemones. Frequent feedings on varied marine foods bring breeders into condition; FishBase gives a tropical range of about 22-28 degrees Celsius. A planted or macroalgae-rich tank both feeds the fish and supplies settling substrate for later juveniles.

Breeding Setup

Set up a mature tank with macroalgae or seagrass-like structure and open patches of substrate where the female can deposit her eggs, reflecting the seagrass and rubble habitat the species occupies in the wild. Stable reef parameters around 24-27 degrees Celsius and pH 8.1-8.4 suit a pair. Because the larvae settle directly rather than dispersing, a well-vegetated rearing area is valuable.

Spawning Behavior & Trigger

Spawning is demersal: the pair releases eggs onto an exposed surface within the tank rather than broadcasting them into the water column. Well-conditioned, mature fish (females from roughly 8 cm) spawn readily, and the absence of a long pelagic dispersal phase means the resulting larvae stay associated with the substrate and vegetation rather than drifting away.

Egg & Fry Care

A defining advantage of this species is that reproduction is not tied to an extended pelagic larval phase: juveniles settle directly onto seagrass beds or floating algae such as Sargassum. This relatively short, substrate-associated development has made the species one of the easier marine fishes to rear, and captive-bred juveniles are commonly grown out to roughly 2.5-4 cm before sale.

Common Challenges

Commercial breeders treat the precise larval-rearing protocol as proprietary, so first-food and water-management details for the early larvae are not fully published. The species can be variable in temperament and may occasionally pick at coral polyps, so a breeding pair is best kept in a dedicated tank. Despite these caveats, its direct-settling larvae make it markedly more achievable than most marine species.