Sewellia sp. 'SEW04'

Overview

SEW04 is a provisional form found among shipments of SEW02 and SEW03 and may represent an undescribed species. It requires a stable, mature stream aquarium with abundant grazing surfaces. Prepare oxygenation and a sustained food supply before obtaining it.

Distribution & habitat

The suggested trade origin is the Hue region of central Vietnam, but this remains unconfirmed. Habitat is described as shallow, rapid headwaters and tributaries over bedrock, sand, gravel, and boulders. Sunlit clear water supports rich attached growth, although storm flows can temporarily carry suspended sediment.

Aquarium setup

Use filtration, circulation, and supplementary aeration as needed to maintain clean, oxygen-rich water. A turnover target around 15–20 tank volumes per hour is appropriate. Strong light encourages stone biofilm; regular water changes should not mean removing every grazing surface.

Seasoned wood and tough attached plants can be included, and exposed sponge filters supply additional feeding areas. Fresh tannin-releasing wood may darken the water enough to compromise lighting. Allow the aquarium to mature before introduction and close escape gaps in the lid.

Diet & feeding

Natural grazing focuses on bottom algae and the microorganisms associated with it; insect larvae may be taken opportunistically. Diatoms and soft green growth are more useful than tough brush algae. Gel preparations rich in vegetables and spirulina can supplement the diet, while separately cultured algae stones help when the main aquarium cannot produce enough.

Inspect offered fish for severe thinness. Weakened individuals need uninterrupted suitable feeding without rivals, and recovery may still prove difficult.

Behaviour & compatibility

Genus-level husbandry favors six or more fish to reduce shyness and distribute competition. Dominant individuals defend feeding patches, often males, and may confront one another with raised bodies and opposing bellies.

Consider small current-adapted open-water fishes, stream gobies, or compatible catfish. Similar sucker-bodied fishes do not necessarily compete equally: timid bottom dwellers may be excluded from the best grazing patches. Mixed groups particularly need space, cover, and abundant food.

Sexual dimorphism

Females appear wider from above, with the snout blending smoothly into the pectoral outline. Males are slimmer and square-snouted, with more abruptly projecting pectorals. Mature males carry soft raised structures along the leading pectoral area and upper head.

Breeding

A breeding attempt can adapt methods used for other Sewellia, without treating those results as a SEW04 record. Mature coarse rounded gravel shelters eggs and fry and retains detritus supporting their microscopic food. Add algae-covered rocks and air-driven sponge filtration; a cooler water change is a possible stimulus.

Related species have been seen rising together into the flow before releasing eggs and sperm. Young initially remain among the substrate and need infusoria-sized food. Introduce Artemia nauplii and microworms once they forage above it. Small fry attach poorly to surfaces, so inspect external filtration carefully during maintenance.