Hara Jordani Fish

Hara jordani (sometimes sold under the older synonym Erethistoides jordani) is a tiny "moth catfish," native to slow-flowing, well-vegetated streams and rivers of the lower Ganges and Brahmaputra river systems in northeast India and Bangladesh. It's one of the smallest catfish species commonly available in the hobby, rarely exceeding 3–4cm.

Its broad, flattened head and body -- giving it its "moth" nickname -- is an adaptation for life hiding among leaf litter, roots, and submerged debris on the riverbed, where it spends most of its time motionless and camouflaged, becoming active mainly after dark.

Because of its small size, secretive nocturnal habits, and origin in soft, current-swept water with natural cover, it's a species best suited to a dedicated, quiet nano or species-focused setup rather than a busy general community tank.

This is a genuinely niche, specialist-hobbyist fish rather than a mainstream aquarium staple -- it doesn't appear in most general fishkeeping guides, and much less is documented about it than about common tetras or corydoras. That's part of its appeal for experienced keepers looking for something unusual, but it also means success depends more on replicating its natural conditions closely than on general "easy community fish" advice.

Wild populations forage by sitting motionless against submerged wood or leaf litter, using camouflage rather than speed to avoid predators, then picking off small invertebrates that drift past or crawl over the debris -- behaviour that's very different from an actively swimming, foraging catfish like a corydoras, and worth keeping in mind when planning tankmates and feeding strategy.

Sexing and breeding this species in the home aquarium is rarely documented and not something most keepers should expect to achieve reliably -- most individuals available in the trade are wild-caught or farm-collected from their native range rather than commercially bred, which is one more reason to give a purchased group the best possible chance of long-term survival rather than treating it as an easily replaceable "starter" fish.

Hara Jordani is a rewarding but genuinely specialised fish -- it does poorly in a typical boisterous community tank.

Cover is essential: provide plenty of hiding spots -- leaf litter, driftwood, root tangles, dense planting -- mimicking its natural riverbed habitat. Without cover it stays permanently stressed and hidden.

Gentle current: as a species from flowing water, it appreciates mild-to-moderate water movement rather than still water.

Group size: best kept in a small group of 5+ in a dedicated nano/species setup; individuals are shy and rarely seen without company.

Feeding: nocturnal and a slow, gentle feeder -- small live or frozen foods (micro worms, baby brine shrimp, small bloodworm) offered near dusk work best; it will lose out to fast, competitive tankmates at feeding time.

Not for general community tanks: avoid fast, aggressive, or large tankmates that will outcompete it for food or stress it out of hiding.

Tank size: a small group can be comfortable in a modest nano tank from around 30-45cm upward, since the species doesn't need swimming space so much as a well-furnished, complex bottom layer to hide within -- surface area and cover density matter more here than raw litres.

Lighting: subdued, indirect lighting suits it far better than a bright, high-output planted-tank setup -- floating plants or shade from driftwood/rockwork will encourage more natural daytime activity instead of the fish staying permanently tucked away.

Substrate: a soft sand or fine gravel base, ideally topped with leaf litter (catappa/almond leaves are commonly used and also release mild tannins that suit the species' preference for soft, blackwater-influenced conditions).

Patience at introduction: newly added groups often stay hidden for days to weeks while settling in -- this is normal for the species and not necessarily a sign of a problem, provided water quality is good and the fish are eating (check for slightly rounded bellies or evidence of food disappearing overnight).

Hara Jordani comes from soft, gently acidic blackwater-influenced habitats and does best when that's reflected in the tank.

• pH: 6.0–7.0, leaning slightly acidic
• Hardness: soft, roughly 1–10 dGH
• Temperature: 22–26°C (72–79°F)
• Oxygenation: benefits from gentle-to-moderate flow and good oxygenation, reflecting its native flowing-water habitat
• Filtration: a mature, gently-flowing filter (sponge or hang-on-back with reduced output) suits it better than a powerful canister blasting the whole tank -- it wants moving, oxygen-rich water without being forced to fight a current constantly
• Water changes: smaller, more frequent partial water changes (10-15% weekly) are gentler on this sensitive species than larger, infrequent ones that shift parameters more abruptly

This is a delicate species best kept by hobbyists prepared to give it a quiet, well-planted, low-competition setup rather than a general mixed community tank.

Ammonia and nitrite sensitivity is high for this species relative to its small bioload -- established, mature water is important, and it's not a good candidate for a newly cycled tank. A slow, careful drip acclimation when introducing new stock (rather than a quick temperature-matched dump) noticeably reduces losses, since this species handles abrupt parameter shifts poorly compared to hardier, more commonly traded catfish. Regular water testing during the first month after introduction is worth the extra effort given how much better this species does in stable, mature water.

Because it's a genuinely uncommon species in the trade, sourcing healthy stock and quarantining new arrivals for a couple of weeks before adding them to an established tank is worth the extra care -- losses among newly imported Hara Jordani are more common than with mainstream community fish, largely due to the stress of transport combined with its narrower tolerance for water-quality lapses.