Asian Stone Catfish Care Guide: The Tiny Catfish That Looks Like a Rock

Asian stone catfish (Hara jerdoni) are one of the smallest true catfish species kept in the freshwater hobby, topping out at about 1.25 inches and looking more like a chip of bark than a fish. Their cryptic mottled brown body, spiny anchor-shaped pectoral fins, and absolute stillness make them invisible until you watch the tank for ten minutes and finally notice the "rock" you have been ignoring is actually breathing. They are sold under several names — dwarf anchor catfish, moth catfish, anchor cat, Hara hara (a related species often mislabeled) — and they have a small but devoted following among nano-tank keepers who want something genuinely unusual instead of another corydoras school.

Species Overview#

Natural Habitat#

Asian stone catfish come from the slow-moving hill streams and floodplain pools of northern Bangladesh, eastern India, and parts of Myanmar. The water in these systems is soft, well-oxygenated, and cool by tropical-fish standards, sitting in the mid-60s to mid-70s for most of the year. The substrate is a mix of fine sand, smooth pebbles, and a thick blanket of fallen leaves that builds up along the slower banks. The fish spend their days motionless in the leaf litter and along submerged wood, blending in so well that even researchers collecting them rely on hand-picking through handfuls of debris rather than netting open water.

Adult size

1.25 in (3 cm)

Lifespan

3-5 years

Min tank

10 gallons

Temperament

Peaceful

Difficulty

Intermediate

Diet

Micropredator

Appearance and Size#

Adults max out at roughly 1.2 inches (3 cm), with most store specimens arriving smaller. The body is flattened top-to-bottom — built for sitting on the substrate rather than swimming through open water — and finished in a mottled pattern of browns, greys, and tans that matches twigs, gravel, and dead leaves almost perfectly. The first ray of each pectoral fin is hardened into a strong, serrated spine that locks outward when the fish is alarmed; this is how they get the "anchor catfish" nickname and is also the reason you should never net them. Always catch a stone cat in a small cup or bag — the spines will tangle in mesh and snap.

Lifespan#

Reported captive lifespans run from 3 to 5 years in well-maintained tanks. Keeper anecdotes on hobbyist forums occasionally describe specimens reaching 6 years, but those are outliers. The most common cause of premature death is starvation in mixed community tanks where faster fish strip every feeding before the catfish emerge.

Water Parameters and Tank Requirements#

Ideal Parameters#

Stone cats want cool, soft, slightly acidic to neutral water that mirrors a hill-stream pool. Aim for the following targets and keep them stable — this species reacts poorly to swings.

• Temperature: 64-75°F (18-24°C). Sustained temps above 77°F shorten lifespan.
• pH: 6.5-7.5
• Hardness: 2-12 dGH (soft to moderately soft)
• Ammonia/nitrite: 0 ppm
• Nitrate: under 20 ppm

The cool-water requirement is the trap that catches most new keepers. If you live in a warm climate without air conditioning, or if you plan to house them with tropical community staples like rams or angelfish, the temperature mismatch alone disqualifies the pairing.

Tank Size and Layout#

A 10-gallon nano tank is a comfortable home for a group of 3 to 5 stone cats. Smaller setups (5 gallons) can work for a trio if the tank is heavily decorated and lightly stocked, but the extra water volume in a 10 buffers temperature and chemistry far better. Floor space matters more than height — these are bottom-sitters, not column swimmers.

The two non-negotiable furnishings are a fine sand substrate and a thick layer of dried Indian almond, oak, or beech leaves. Leaf litter does three jobs at once: it gives the catfish camouflage cover, releases tannins that gently soften and acidify the water, and seeds biofilm that nano shrimp and other tank residents graze on. Add smooth river pebbles and a few pieces of driftwood for additional crevices. Plants are optional but appreciated — Java fern, Anubias, and Cryptocoryne all tolerate the cooler temperatures.

Filtration and Flow#

A small sponge filter rated for the tank size is the right call. Stone cats are sensitive to low oxygen but cannot handle the river-current flow that comes out of an oversized HOB or canister return. A sponge filter delivers gentle, even circulation and aerates the water without blasting the leaf litter into a tornado. If you prefer a hang-on-back, choose one with an adjustable flow rate and aim the output at the glass to break the current.

Diet and Feeding#

Natural Diet and Captive Staples#

In the wild, stone cats feed on micro-invertebrates — tiny worms, insect larvae, and crustaceans they ambush from the leaf litter. In the home tank, they accept a similar menu of small frozen and live foods.

• Frozen: bloodworms, daphnia, cyclops, baby brine shrimp, micro-worms
• Live: blackworms, white worms, vinegar eels (especially during conditioning)
• Dry: quality sinking micro-pellets and crushed wafers, used as a backup rather than a staple

Variety beats any single food. A rotation of two or three frozen foods plus the occasional live treat keeps weight on them and triggers natural foraging behavior.

Feeding Tips#

Stone cats are nocturnal and slow. They will not race a school of tetras to a falling pellet and will quietly starve in a tank where they "look healthy" because they are still hiding. Two habits keep them fed:

1. Feed after lights-out. Drop their food into the tank ten or fifteen minutes after the room goes dark. Use a turkey baster to deliver food directly into the leaf-litter zone where they actually live.
2. Target-feed individuals. When you spot one, drift a small amount of food close enough that it can claim it without competing.

Tank Mates and Compatibility#

Suitable Companions#

Stone cats want quiet, peaceful, similarly tiny tank mates that share their cool-water preference and won't strip every meal. Good pairings include:

• Ember tetras
• Celestial pearl danios (galaxy rasboras)
• Chili rasboras and other Boraras species
• Pygmy corydoras — share the bottom but are too small to bully them
• Panda corydoras for cooler community setups
• Dwarf shrimp (neocaridina, smaller caridina) — adults are ignored

A planted nano with a small school of chili rasboras up top, a group of pygmy cories grazing the open sand, and three to five stone cats hiding in the leaf litter is one of the most charming biotope-style setups you can build in a 10-gallon tank.

Species to Avoid#

Anything large enough to swallow a 1-inch fish — even peacefully — is off the list. That rules out most cichlids (including dwarf species like rams and apistogramma when adults), gouramis, larger barbs, angelfish, and any predatory tetra. Also skip boisterous fast-feeders like zebra danios and most tiger barbs; they will not attack the catfish but they will starve them by eating everything that hits the water.

Breeding#

Breeding Conditions#

Captive breeding of Hara jerdoni is rare and not commercially established. The species has been spawned by dedicated hobbyists in soft, slightly acidic water with dense cover, often after a cool-water seasonal change that mimics monsoon-driven temperature drops. Eggs are deposited on submerged leaves or substrate, and reports suggest the male may briefly guard the clutch before the parents lose interest.

Raising Fry#

Fry are extremely small and sensitive to water-quality fluctuations. First foods are infusoria and micro-worms, graduating to baby brine shrimp once the fry can take them. Most keepers who attempt breeding move spawning adults to a dedicated, mature tank and accept that fry survival rates will be low. If you successfully raise a clutch, your local fish-keeping club will line up to trade for them — captive-bred stone cats are essentially nonexistent on the market.

Common Health Issues#

Sensitivity to Copper and Medications#

Like most small scaleless and lightly scaled catfish, stone cats are intolerant of copper-based medications. Standard ich treatments built around copper sulfate or chelated copper will kill them faster than the parasite. Use catfish-safe alternatives: heat (raise the tank to 82-84°F for ich, briefly — and accept the short-term temperature stress as the lesser evil), salt at low doses if the species you are treating tolerates it, or formalin and malachite green at half-dose, watched closely.

Always quarantine new tank mates separately for 2-4 weeks. Keeping ich and velvet out of the display in the first place is far easier than treating it around copper-sensitive fish.

Stress and Hiding Behavior#

A stone cat that has nowhere to hide is a stressed stone cat. Symptoms of chronic stress include refusing food, resting in the open with clamped fins, and rapid gill movement. The fix is almost always more cover — add another piece of driftwood, double the leaf litter, or pull a noisy tank mate. Their default state is invisible. If you can see them clearly all day, the layout is wrong.

Where to Buy and What to Look For#

Finding Healthy Specimens at Your Local Fish Store#

Stone cats are a rare-stock fish at most local stores. They show up in mixed shipments from wholesalers like Segrest or Aquatropic a few times a year, and small specialty shops are the most likely places to see them. Walk in expecting to find none, ask whether they can be special-ordered, and have realistic patience — a good shop manager will flag the species in their next order if you ask.

When you do find a tank, look for:

• Active grazing or at least alert response when the tank is approached (they are still shy, so "calm but watching" is fine)
• No visible white spots, fungus patches, or red lesions
• Intact pectoral spines and clear eyes
• Evidence the fish are eating in the store tank — ask the staff to feed in front of you

Avoid any specimen that looks sunken behind the head (a sign of long-term starvation) or hangs at the surface gulping air, which suggests gill damage or oxygen problems.

Online Availability#

Specialty nano-fish vendors and rare-fish importers occasionally list Hara jerdoni online, often as "Asian stone catfish," "moth catfish," or "dwarf anchor catfish." Read the seller's reviews carefully — wild-caught micro-catfish are stressed by long shipping, and a vendor with a strong live-arrival guarantee and recent positive feedback is worth a few extra dollars over the cheapest listing. Buying through a local fish store that can quarantine the fish for a week before pickup is almost always the better outcome than direct ship-to-door.

A cool, planted, leaf-littered nano tank — for example a Fluval Flex 9 or 15 styled around blackwater botanicals — is the kind of display these fish were essentially designed for.

Quick Reference#

• Tank size: 10 gallons minimum for a group of 3-5
• Temperature: 64-75°F
• pH: 6.5-7.5
• Hardness: 2-12 dGH
• Diet: Micropredator — frozen bloodworms, micro-worms, daphnia, sinking micro-pellets
• Tankmates: Ember tetras, celestial pearl danios, chili rasboras, pygmy/panda corydoras, dwarf shrimp
• Avoid: Cichlids, gouramis, larger tetras, fast-feeding barbs and danios, copper-based medications
• Lifespan: 3-5 years
• Max size: 1.25 in (3 cm)
• Difficulty: Intermediate — easy once setup is right, unforgiving of warm water and food competition