Upside-down Catfish

Habitat and Natural Environment

The Upside-down Catfish (Synodontis nigriventris) is a small African mochokid catfish native to the Congo River Basin (notably the central Congo/Ubangi systems). In the wild it inhabits slow to moderate-flowing rivers and flooded forest margins where wood tangles, roots, leaf litter, and shaded banks provide cover and grazing surfaces.

Its trademark “upside-down” swimming posture is an adaptation for feeding along the underside of branches and other submerged structures, where it grazes biofilm and picks at small invertebrates. Natural waters are typically warm, oxygenated, and slightly acidic to neutral, with plenty of structure and dimmer lighting under canopy cover.

Tank Setup Requirements

Tank Size and Stocking

A 20-gallon (75 L) aquarium can work for a small group, but 30 gallons (110 L) or larger is recommended for best behavior and stability. This species is social and usually does best in groups of 4–6+; solitary individuals are often shyer and more reclusive.

Water Parameters

• Temperature: 24–27°C (75–81°F)
• pH: ~6.5–7.5 (tolerant slightly outside this with stability)
• Hardness: soft to moderately hard (roughly 3–15 dGH)
• Filtration: efficient biological filtration; moderate flow preferred
• Maintenance: regular partial water changes (e.g., 25–40% weekly, adjusted to stocking)

Aquascape, Substrate, and Lighting

Provide lots of cover: driftwood, rock caves, coconut hides, and dense plantings (live or artificial) help them feel secure and encourage natural upside-down cruising under overhangs. A sand or smooth fine gravel substrate is ideal to protect barbels and reduce abrasion while foraging.

• Include multiple hiding spots so group members can avoid crowding
• Use driftwood/branches to create shaded “ceilings” to browse underneath
• Dim to moderate lighting; floating plants can help diffuse bright light
• Ensure all decor has smooth entrances (avoid sharp edges that can snag fins)

Feeding and Diet

Upside-down Catfish are omnivorous scavenger-grazers. In aquariums they thrive on a varied diet that combines quality sinking staples with meaty and plant-based additions. They often feed most confidently at dusk and after lights-out.

• Staples: sinking pellets/tablets formulated for catfish or omnivores
• Protein foods (2–4x weekly): frozen/thawed bloodworms, brine shrimp, daphnia, mysis, chopped earthworms
• Plant matter (regularly): spirulina wafers, blanched zucchini/spinach/peas (small portions)
• Occasional treats: Repashy-style gel foods (bottom-feeder or community blends)

Behavior and Temperament

This species is peaceful, social, and generally compatible with calm community fish of similar size. They spend much of their time under cover, moving in short bursts and often swimming inverted beneath wood and leaves. In groups they are more active and visible.

• Temperament: peaceful; mild intraspecific jostling is normal
• Activity: crepuscular/nocturnal leaning (most active at dusk/night)
• Tankmates: tetras, rasboras, peaceful barbs, dwarf cichlids with similar water needs, other non-aggressive bottom dwellers
• Avoid: very aggressive fish, fin-nippers, and large predatory species

Breeding (if applicable)

Breeding Upside-down Catfish in home aquariums is uncommon. Commercial production is often achieved with hormonal induction. In standard community tanks, adults may court but rarely yield consistent, survivable spawns without specialized setup and conditioning.

• Sexing: difficult; females may appear slightly rounder when mature/conditioned
• Spawning triggers (general): heavy conditioning, warm stable water, and large water changes that mimic seasonal influx
• Egg/larval care: if spawning occurs, eggs and fry may be eaten unless separated
• Best practice: consider breeding attempts “advanced” due to low reliability without specialized methods

Health and Common Issues

Upside-down Catfish are hardy when kept in clean, stable water with adequate shelter. Most health issues stem from poor water quality, stress from bright/open tanks, or inappropriate substrates/decor that damage barbels and skin.

• Barbel erosion/infections: often linked to rough substrate, dirty substrate, or chronic poor water quality
• Ich (white spot): typically introduced with new fish; more likely during stress or temperature swings
• Fin damage/scrapes: from sharp décor or bullying tankmates
• Bloat/constipation: from overfeeding rich foods without enough fiber/variety
• Sensitivity considerations: many catfish can be sensitive to certain medications; confirm suitability and dose carefully