Twig Catfish Care Guide: Tank Setup, Diet & Expert Tips for Farlowella acus

Species Overview#

Twig catfish (Farlowella acus) are among the most distinctive freshwater catfish in the hobby — long, pencil-thin loricariids that look more like a piece of waterlogged stick than a fish. They drift across driftwood and broad plant leaves at a slow grazing pace, blending into the hardscape so well that newcomers routinely lose track of them in their own tanks. Hobbyists who keep them well report years of quiet, peaceful behavior and a remarkably effective algae crew member for soft-water community setups.

The species has a reputation for being delicate, and the reputation is earned. Twig catfish do not tolerate the same shortcuts other catfish forgive — uncycled tanks, copper-based medications, sterile glass, and high-protein staple diets all kill them, often slowly enough that the keeper does not connect cause to effect for weeks. This guide focuses on the husbandry decisions that separate a thriving twig catfish from one that quietly starves in a beautiful tank.

Adult size

6-8 in (15-20 cm)

Lifespan

10-15 years

Min tank

30 gallons

Temperament

Peaceful

Difficulty

Intermediate

Diet

Herbivore (biofilm/algae)

Natural Habitat#

Wild Farlowella acus live in slow-moving tributaries and flooded margins of South American river systems, with the most-cited collection regions running through Venezuela and Colombia (the exact range varies by taxonomic source — the Farlowella genus is large and routinely revised). They favor shaded, tannin-stained water packed with submerged wood, leaf litter, and broadleaf vegetation. The bottom is typically sand or fine substrate with no sharp rock — important context for tank setup.

The water in their native habitat is soft, acidic, and oxygen-rich despite low flow, with dissolved tannins from decaying leaf litter staining everything tea-colored. Replicating this — soft water, smooth surfaces, plenty of grazable wood — is the difference between a twig catfish that lives a decade and one that dies within six months.

Appearance & Size#

The body is the calling card. Farlowella acus stretches into an extreme elongated form with a tapered rostral extension off the snout, giving the fish the unmistakable silhouette of a brown twig. Coloration runs olive-brown to grey-brown with subtle darker mottling along the dorsal surface, providing nearly perfect camouflage against driftwood and leaf litter. Look for the fish at the center of broad sword leaves or pressed against vertical pieces of bogwood — they rarely move when observed.

Adult length runs 6 to 8 inches (15 to 20 cm), with most captive specimens settling around 6 inches. The slender profile makes them look smaller than they are; a 7-inch twig catfish has roughly the body mass of a 3-inch tetra. Despite the modest mass, they need swimming and grazing room — a 30-gallon tank with a long footprint is the realistic minimum.

Lifespan#

In well-maintained aquariums, twig catfish typically live 10 to 15 years. That number assumes stable parameters, copper-free medications, a varied plant-based diet, and a low-stress environment. Stress-sensitive fish lose years quickly: a twig catfish kept in an immature tank with boisterous tank mates and irregular feeding will more often fade in 1 to 2 years rather than reach the species' real potential.

Water Parameters & Tank Requirements#

Twig catfish are not parameter-sensitive in the sense that wild discus or chocolate gouramis are — they tolerate a reasonable range of pH and hardness. What they cannot tolerate is biological instability: fluctuating ammonia, swinging nitrate, sudden temperature changes, or any trace of copper.

Ideal Water Parameters#

Target a temperature between 75°F and 82°F, with the sweet spot around 78°F. Anything above 82°F drops dissolved oxygen and accelerates their metabolism past the point their slow grazing can sustain. Below 73°F, they slow further and become more susceptible to bacterial infection.

Keep pH between 6.0 and 7.0, ideally trending toward the lower end of that range. Hardness should sit in the soft to moderately soft range — 2 to 12 dGH is the commonly cited window, though most experienced keepers report best success below 8 dGH. Verify the upper hardness tolerance against your local tap water before stocking; some lines bred in moderately hard water adapt better than wild-type imports.

The non-negotiable parameters: ammonia and nitrite must read 0 ppm at all times, and nitrate should stay under 20 ppm. Twig catfish are exceptionally sensitive to ammonia and nitrite spikes — even brief excursions visibly stress them, and chronic low-level ammonia is one of the most common causes of slow decline. Test weekly during the first three months of ownership and after any tank changes.

Tank Size & Layout#

A 30-gallon tank is the realistic minimum, and a 40-gallon long is better. Footprint matters more than vertical height for a species that spends nearly all its time clinging to horizontal and vertical surfaces. Plan the layout around grazing real estate rather than open swimming space.

Heavy planting and abundant driftwood are essential, not decorative. Broadleaf species — Amazon swords, anubias, larger crypts — give the fish vertical and horizontal surfaces to graze and rest on. Multiple pieces of smooth bogwood or Malaysian driftwood provide both grazing substrate and cover. Use sand or fine smooth gravel for the substrate; sharp rocks and aggressive aquascaping cause skin abrasions on the fish's belly as it slides across surfaces.

Flow should be low to moderate. Strong powerhead currents push twig catfish off their grazing surfaces and stress them. A planted-tank-style flow pattern — gentle circulation with a few quiet spots — works best.

Filtration & Water Quality#

Gentle but effective filtration is the goal. A canister filter sized one tank-class above the actual tank volume gives you the biological capacity without overwhelming flow, especially when paired with a wider spray bar that disperses the return. A large sponge filter (or two) driven by a quality air pump also works well and provides additional surface agitation for oxygenation.

Weekly water changes are critical — 25 to 30 percent is the standard for a moderately stocked tank. Do not skip weeks. Twig catfish reflect chronic poor maintenance faster than most species, and once nitrate creeps above 20 ppm consistently, they begin losing weight and color.

Avoid copper-based treatments entirely. Loricariid catfish absorb copper readily across their gill surfaces and respond poorly even at "fish-safe" doses sold for ich and external parasites. If you need to medicate the display tank, choose copper-free alternatives or remove the twig catfish to a separate hospital tank with conservative dosing.

Lighting#

Low to moderate lighting works best. Dense plant cover and floating plants reduce stress, mimic the natural shaded habitat, and discourage twig catfish from hiding in the deepest cave at all hours. Bright, open lighting over a sparse hardscape will keep them pressed against the back glass instead of grazing in the open. Aim for 6 to 8 hours of moderate-intensity light per day, ideally on a timer for consistency.

Diet & Feeding#

The single most common cause of twig catfish decline in home aquariums is starvation in a tank that looks well-maintained. Their diet is narrow, their feeding pace is slow, and they do not compete with faster fish for food.

Primary Diet#

Twig catfish are biofilm and algae grazers. In a healthy mature tank, the natural film on glass, driftwood, leaves, and decor provides a baseline of nutrition that the fish grazes continuously through the day. This biofilm layer is the foundation — without it, no amount of supplementary feeding fully replaces what the fish needs.

Supplement that base with a rotation of plant-based foods. Blanched zucchini and cucumber slices are the gold standard — cut a half-inch slice, microwave it in water for 30 to 45 seconds until soft, weigh it down with a fork or veggie clip, and drop it in. Replace every 24 hours to prevent fouling. Spirulina wafers and high-quality sinking algae tabs (Hikari Algae Wafers, Omega One Veggie Rounds) round out the rotation.

Feeding Challenges#

Twig catfish are shy, slow feeders. Faster tank mates — even peaceful ones like tetras and rasboras — will reach a sinking wafer or zucchini slice before the twig catfish notices. Feed at lights-out, place sinking foods near the twig catfish's preferred resting spot, and consider target-feeding by hand-placing a wafer next to the fish if you keep them with a busy community.

Watch the belly. A healthy twig catfish has a slightly rounded underside; a starving one looks visibly hollow between the pelvic fins and the body wall. By the time the belly looks sunken, the fish is in trouble — adjust feeding before that point, not after.

Foods to Avoid#

Skip high-protein staple foods. Bloodworms, beef heart, and protein-heavy commercial pellets cause digestive issues and bloat in twig catfish, which evolved as nearly pure herbivores. The diet should remain plant-based with occasional incidental protein from biofilm. They will not benefit from the mosquito larvae and frozen foods that suit most community fish.

Tank Mates & Compatibility#

Twig catfish are entirely peaceful and ignore other tank inhabitants almost completely. The compatibility question runs the other direction — what is safe for them, not what is safe from them.

Ideal Community Partners#

The best twig catfish community is small, peaceful, and uses different parts of the tank. Strong choices:

• Small peaceful tetras — neon tetras, ember tetras, cardinal tetras, rummynose tetras
• Small rasboras — chili rasboras, harlequin rasboras, lambchop rasboras
• Dwarf corydoras — pygmy corydoras and dwarf cory species share the bottom but feed on dropped food, not algae
• Otocinclus — share the same algae-grazer niche and identical care requirements
• Pencilfish — slow-moving and similar size class
• Neocaridina or Caridina shrimp — pair extremely well with twig catfish in soft-water tanks

A great mature soft-water tank for twig catfish might pair them with a school of 10 ember tetras, a group of 6 to 8 otocinclus, a colony of cherry shrimp, and the twig catfish themselves — three different grazers and a peaceful midwater school sharing the available food without competing.

Species to Avoid#

Avoid anything aggressive, boisterous, or fast-feeding. Specific bad pairings include:

• All cichlids — angelfish, kribensis, rams, and apistogrammas all harass twig catfish, and larger New World cichlids are dangerous
• Larger barbs — tiger barbs and rosy barbs nip the trailing rostrum and tail
• Larger gouramis — opportunistic and territorial in a way that drives twig catfish into permanent hiding
• Larger plecos — common plecos and large-bodied bristlenose outcompete twig catfish for grazing surface and may rasp slime coat from their bodies
• Bettas — temperament-dependent, but the risk is not worth it in shared territory
• Anything that feeds aggressively at the front glass — even peaceful danios can simply consume all sinking food before twig catfish notice it

Keeping Multiple Twig Catfish#

Twig catfish are not strictly schooling, but they live well in small groups in tanks with adequate space. Males can be mildly territorial, especially during spawning attempts — provide visual breaks (driftwood pieces, dense plant clusters) so subordinate males can stay out of sight when needed. The commonly recommended ratio favors more females than males, though specific sex ratios are debated and worth verifying against current breeder reports for the Farlowella genus before setting up a breeding group. A 40-gallon long can hold a trio (one male, two females) comfortably.

Breeding#

Twig catfish breed in well-managed home aquariums, though successful fry rearing is the bottleneck for most hobbyists.

Sexing Farlowella acus#

Mature males develop rostral odontodes — bristly, hair-like structures along the snout and the leading edge of the pectoral fins. Females lack the bristles or show only a sparse fringe along the snout edge. Females also become noticeably broader through the body when gravid, with a fuller midsection visible from above.

Sexing is reliable once fish reach adult size (around 5 inches and up). Juveniles below 4 inches are difficult to sex with confidence.

Spawning Conditions#

Twig catfish are flat-surface spawners. Females deposit clusters of eggs on broad leaves (Amazon sword leaves are a favorite), pieces of slate, or even the front glass of the aquarium. The male guards and aerates the eggs until hatching, fanning them with his fins and chasing off any fish that approach.

The common trigger for spawning is a slight water change with cooler, slightly softer water — mimicking a rainy-season influx. A 30 percent water change with water 2 to 4°F cooler than the tank often initiates spawning behavior within 24 to 48 hours in a well-conditioned pair. Eggs hatch in roughly 6 to 9 days at standard temperatures.

Raising Fry#

Fry are extremely delicate and require a biofilm-rich environment to survive the first few weeks. Feed infusoria, liquid fry food, or commercial biofilm cultures (Bacter AE works well) for the first 10 to 14 days, then transition to powdered spirulina and tiny fragments of blanched zucchini once the fry begin actively grazing. A heavily planted, mature rearing tank with abundant biofilm gives the highest survival rate. Bare-bottomed fry tanks generally fail with this species.

Common Health Issues#

Most twig catfish health problems trace back to two root causes: physical injury from rough decor, and chronic stress from poor parameters or aggressive tank mates. Direct disease is comparatively rare in well-kept fish.

Bacterial Infections & Wounds#

Twig catfish are prone to skin abrasions and bacterial infections at the abrasion sites because of how they slide across surfaces. Sharp rocks, jagged driftwood, and rough lava rock cause cuts on the underside that quickly become infected in tanks with elevated organic waste.

The fix is environmental: use smooth driftwood, fine sand or smooth gravel, and avoid rough decor entirely. If you spot a wound, do an immediate large water change, lower nitrate, and observe. Antibiotics are a last resort and should be chosen carefully to avoid copper or other compounds toxic to loricariids.

Ich & Parasites#

Twig catfish are highly sensitive to standard ich treatments. Copper-based medications are off-limits entirely — they kill catfish and shrimp at therapeutic doses. Salt is also poorly tolerated and stresses the species more than it helps.

If ich appears, treat with heat alone where possible — slowly raise the tank to 84°F over several days and hold for 10 to 14 days. If medication is required, dose at half-strength of the manufacturer's recommendation and watch the fish closely for stress. Move treatment to a hospital tank rather than dosing the display whenever practical.

Stress-Related Decline#

The most common cause of twig catfish death in home aquariums is not disease — it is chronic, low-grade stress that depresses the immune system over weeks or months. Symptoms include faded color, reduced grazing, hiding constantly, and slow weight loss despite available food.

The triggers are stable parameters violated, busy tank traffic (placement near a high-traffic doorway), aggressive tank mates, and chronic poor water quality. The fix is environmental rather than medical: stable parameters, quiet tank placement, peaceful tank mates only, and weekly water changes without exception.

Where to Buy & What to Look For#

Twig catfish quality varies significantly between sources. A well-acclimated, well-fed specimen from a knowledgeable local store has a dramatically better chance of surviving the move to your tank than a stressed import that has just cleared quarantine.

Sourcing Healthy Specimens#

Inspect the store's tank before inspecting any individual fish. Look for: visibly grazing twig catfish on driftwood or glass, no dead specimens in the system, the presence of biofilm or algae somewhere in the tank, and quiet positioning rather than fish hanging at the surface.

Once a tank passes inspection, watch the individual fish you are considering for at least five minutes. Healthy twig catfish cling to surfaces and graze in slow, deliberate movements with the body relaxed and the tail trailing naturally. Look for: rounded (not sunken) belly, intact rostrum with no chips or damage, no visible wounds or cuts on the body underside, fully extended fins with no fraying, and active grazing behavior on driftwood or glass.

Avoid any specimen with a sunken belly, broken rostrum, visible wounds, or that hangs listlessly at the surface. Twig catfish in trouble rarely recover after purchase — pass on the questionable fish and wait for a better shipment.

Local Fish Store vs. Online#

A good local fish store wins for twig catfish. Inspecting the fish in person is genuinely diagnostic for this species — belly fullness, rostrum condition, and grazing behavior are not visible in product photos, and a stressed twig catfish in a shipping bag often does not recover. Local store purchases also let you start drip acclimation within an hour of leaving the shop, rather than after a 24-hour shipping leg.

Online vendors do their best with fragile species, but losses are meaningfully higher for twig catfish than for hardier community fish, and live-arrival guarantees do not undo the stress that triggers a slow post-arrival decline.

When you bring a new twig catfish home, drip-acclimate slowly over 60 to 90 minutes. The species is sensitive to sudden changes in pH, temperature, and conductivity — a slow drip line giving the fish 90 minutes to adjust pays back in survival. See our acclimation guide for the full step-by-step.

If you keep brown algae or diatoms going in your tank, that is good news for a new twig catfish — see our brown algae guide for help reading what your tank is telling you about its readiness. For more on inspecting freshwater stock generally, see our freshwater fish guide, and for related grazer species, our bristlenose pleco and otocinclus write-ups cover the most common companion algae crew choices.

Quick Reference#

• Tank size: 30 gallons minimum; 40-gallon long preferred
• Temperature: 75-82°F (sweet spot 78°F)
• pH: 6.0-7.0, soft to moderately soft (2-12 dGH)
• Ammonia/Nitrite: 0 ppm at all times
• Nitrate: under 20 ppm
• Tank maturity: 3-4 months minimum past cycling; visible biofilm and soft algae required
• Diet: Biofilm and soft algae primary; supplement with blanched zucchini, cucumber, spirulina wafers, and sinking algae tabs
• Best tank mates: Small tetras, small rasboras, dwarf corydoras, otocinclus, shrimp
• Avoid: Cichlids, larger barbs, larger gouramis, larger plecos, copper-based medications, jagged decor
• Lifespan: 10-15 years in well-maintained tanks
• Difficulty: Intermediate — parameters forgiving, but biofilm dependence and copper sensitivity unforgiving