Sphaerichthys acrostoma · Giant Chocolate Gourami

Overview

Sphaerichthys acrostoma is a mouthbrooding labyrinth fish from Borneo's Mentaya system, sold under several giant- or sharp-nosed-chocolate labels. Slow movement calls for quiet company and small foods. Males carry the brood, unlike the female mouthbrooding of some other chocolate gouramis.

Distribution & habitat

It is known from the Mentaya drainage in Indonesian Borneo, including records near Sampit. Peat swamps and black-water streams predominate, although some clear-water occurrence is possible. Typical habitat is shaded, very soft, and acidic, with fallen branches and leaves. Forest alteration affects these environments.

Aquarium setup

Allow at least about 80 × 30 cm of floor space. Soft sand, roots, and branches create shaded caves; pots and pipes also provide useful refuges. Dried leaves add cover and microbial communities that supplement fry food.

Dim lighting, shade-tolerant plants, and floating cover are suitable. Keep water movement gentle. In lightly stocked aquariums, weekly changes of about 10–15% are appropriate, avoiding sudden large changes. Maintenance and feeding should account for the fish's sensitivity to competition and disturbance.

Diet & feeding

It mainly hunts small aquatic crustaceans, worms, insect larvae, and other zooplankton. New arrivals may reject prepared food, although some learn to accept it. Supply daily small live or frozen foods such as brine shrimp nauplii, Daphnia, microworms, or Grindal worms.

Behaviour & compatibility

Larger or vigorous fish can intimidate it and monopolize food. Choose small peaceful companions with matching requirements. At least six conspecifics support interaction, despite the absence of tight schooling. Groups develop hierarchies, and dominant fish may exclude rivals from food or favored places; monitor subordinate feeding.

Sexual dimorphism

Excited or courting males show a stripe from the tail base to midbody. Females lack it, instead showing darker scale rows on the lower front body and along the anal-fin base. Females also have more red on the throat and unpaired fins, a sharper head, and a straighter lower jaw. The male's rounder jaw has expandable skin for brooding.

Breeding

Males mouthbrood in pairs or groups. Courtship normally begins with a female, or the dominant female in a group. Nearly upright embraces precede eggs being deposited and fertilized on the substrate, then gathered directly by the male. Both adults defend the area during spawning.

A brooding male retreats and eats little or nothing. After about seven to twenty days he releases roughly ten to forty swimming young. He can be moved cautiously to separate accommodation a few days after spawning, or released fry transferred individually, using matching water chemistry and temperature. Mature planted aquariums may retain some offspring naturally.

Fry immediately accept microworms and brine shrimp nauplii. Daily water changes around 10% support rearing. A tight lid retains warm humid air needed for normal labyrinth development.

Notes

Sex-specific patterns distinguish this fish from more distinctly pale-barred chocolate gouramis. Check flank markings, head shape, red pigmentation, and provenance rather than relying on sales labels.