Ghost Catfish Care Guide: The Living Glass Fish for Your Freshwater Tank

Species Overview#

Ghost catfish (Kryptopterus vitreolus) are the see-through schooling fish you have probably spotted hovering mid-tank at a fish store, looking less like an animal and more like a swimming x-ray. The body is genuinely transparent — you can count the vertebrae, watch the heart beat, and trace the swim bladder through the skin. They come from slow, tea-stained rivers in Thailand and peninsular Malaysia, where they drift in tight schools beneath overhanging vegetation. In the hobby they are the same fish people call glass catfish, and the two names refer to one species despite decades of label confusion at retail.

These fish reward keepers who understand schooling species and pay attention to water quality. They punish careless setups quickly. A single ghost catfish dropped into a community tank will hide, refuse food, and waste away within weeks. A school of six or more in a planted, gently filtered tank will glide together in a synchronized line, pectoral fins flickering, and become one of the most arresting displays in freshwater aquaria.

Adult size

2.5-3 in (6-8 cm)

Lifespan

5-8 years

Min tank

20 gallons (long)

Temperament

Peaceful shoaler

Difficulty

Intermediate

Diet

Micropredator

Why They're Called "Ghost" Fish#

The transparent body is the obvious answer, but the effect is more striking in person than in photos. Light passes straight through the muscle and skin, leaving only the spine, internal organs, and a silvery sac near the gills visible. As the fish moves, faint iridescent flashes of blue and green ripple along the flanks. In a school, the bodies overlap and merge into a single ghostly shape suspended in the water column.

Pet stores label these fish as both ghost catfish and glass catfish, and the names are used interchangeably for K. vitreolus. A second species, Kryptopterus bicirrhis, gets mislabeled as glass catfish on shipping invoices, but it is a larger, rarer fish that almost never enters the trade. If your store catfish are under three inches and transparent, you have K. vitreolus.

Natural Habitat#

Ghost catfish inhabit slow-moving blackwater rivers and forest streams across central and southern Thailand and into peninsular Malaysia. The water is soft, slightly acidic, and tinted with tannins from decaying leaf litter. Schools shelter under root tangles and beneath floating plants during the day, then move out to hunt small invertebrates as the light fades. Replicating that habitat — gentle current, dim light, dense plant cover — is the single biggest factor in keeping them alive long-term.

Size and Lifespan#

Adults reach 2.5 to 3 inches. With clean water, a stable school, and a varied diet, they live 5 to 8 years. Most ghost catfish that die early die from poor schooling numbers or chronic ammonia exposure during cycling, not from old age.

Water Parameters & Tank Requirements#

Ghost catfish are scaleless and lack a heavy mucus layer, which makes them more sensitive to dissolved toxins than tetras or rasboras of similar size. Stable parameters matter more than perfect numbers.

Ideal Water Conditions#

Aim for 75-80°F, pH 6.5-7.5, and hardness of 5-12 dGH. The fish can adapt to slightly harder water with patient acclimation, but they thrive in soft, mildly acidic conditions that mirror their native blackwater streams. Ammonia and nitrite must read zero. Nitrate should stay under 20 ppm — they are particularly sensitive to nitrate creep in under-maintained tanks. A weekly 25 percent water change, with temperature-matched and dechlorinated replacement water, keeps parameters stable. See our freshwater fish overview for cycling fundamentals before adding any livestock.

Tank Size and Setup#

A 20-gallon long is the practical minimum for a school of six. The horizontal footprint matters more than total volume because ghost catfish are mid-water swimmers that cruise back and forth in formation. A 29 or 40 long is a better long-term home and gives the school room to develop natural behavior. Stock the tank with dense vertical plants — Java fern, hornwort, Amazon swords, vallisneria — and add driftwood to break up sightlines. A few floating plants on the surface diffuse the lighting and give the school a sense of cover. See our 20-gallon fish tank guide for a stocking framework that fits a small ghost catfish school.

Filtration and Flow#

Gentle filtration is non-negotiable. A sponge filter rated for the tank size, a baffled hang-on-back, or a canister with the return aimed at the back glass all work. Ghost catfish dislike strong current and will exhaust themselves trying to hold position against a powerhead. If you can see the school swimming sideways or struggling to maintain place, the flow is too high.

Lighting#

Subdued lighting suits them best. Bright LEDs on a bare-bottom tank will keep ghost catfish hiding behind the filter intake all day. Floating plants — frogbit, dwarf water lettuce, salvinia — diffuse intensity and shade the water column. The school becomes far more active in soft, broken light.

Diet & Feeding#

Ghost catfish are micropredators that feed in the open water column rather than along the substrate. This catches new keepers off guard, because most catfish in the hobby are bottom scavengers.

What Ghost Catfish Eat#

In the wild they hunt zooplankton, mosquito larvae, small crustaceans, and insect drift. In captivity they readily accept frozen bloodworms, frozen daphnia, frozen brine shrimp, and live blackworms. Many specimens initially refuse dry food. Once they are settled and feeding well on frozen foods, you can train most ghost catfish to take high-quality crushed flakes or micro-pellets that drift slowly through the water column.

Feeding Tips for Shy Eaters#

Feed at dusk or with the room lights dim. Ghost catfish are crepuscular and feed more confidently in low light. If a fish is not eating, target-feed thawed bloodworms with a long pipette or turkey baster directly into the school's swimming zone. Two small feedings per day produce better growth and color than one large feeding. Remove any uneaten frozen food after a few minutes — it fouls the water fast in a tank that already runs gentle filtration.

Schooling Behavior & Tank Mates#

This is where ghost catfish keepers most often go wrong. Stocking is not a stylistic choice with this species — it is a survival requirement.

Why You Must Keep Them in Groups#

Ghost catfish school for both safety and signaling. In a proper group they hold formation in mid-water, fins angled to read the movements of neighbors. Strip the school down to two or three and the social structure collapses. The remaining fish hide behind decor, refuse food, lose color, and die from chronic stress. There is no workaround for this — the school size is the care requirement.

Compatible Tank Mates#

Stick to small, peaceful community species that share the same gentle-water preferences. Harlequin rasboras, ember tetras, neon tetras, cardinal tetras, and pygmy or panda corydoras all work well. Honey gouramis and dwarf gouramis can share the tank if the gourami is not aggressive at feeding time. Avoid tiger barbs, serpae tetras, and any other known fin-nipper — the ghost catfish's translucent fins are easy targets. Skip large cichlids, oscars, and predatory species entirely.

Invertebrate Compatibility#

Adult Amano shrimp, nerite snails, and mystery snails are generally safe. Ghost catfish may pick at neocaridina (cherry shrimp) fry if they encounter them, but established adult shrimp are usually ignored. If you keep a dedicated shrimp colony, house the ghost catfish in a separate tank.

Common Health Issues#

Ghost catfish are scaleless, which changes the disease and treatment math compared to scaled species.

Ich and Skin Flukes#

White spot disease (ich) shows up clearly on the transparent body, usually first as a few salt-grain dots on the fins or tail. Treat at half-dose with salt-free, scaleless-safe ich medication. Many keepers also raise temperature to 82°F to accelerate the parasite's life cycle and shorten treatment. Avoid copper-based medications and skip aquarium salt — both can stress scaleless catfish.

Stress-Related Decline#

The most common cause of death in ghost catfish is not disease at all. It is chronic stress from undersized schools, loud vibrations near the tank, frequent rescaping, or unstable water parameters. A stressed ghost catfish goes pale, hides constantly, and refuses food. By the time secondary infection sets in, the fish is usually too compromised to recover. Address the underlying stressor first — water quality, schooling numbers, or tank disturbance — before reaching for medication.

Where to Buy & What to Look For#

Most chain pet stores stock ghost catfish in groups of one or two, often in tanks with too much flow and too much light. The fish in those tanks are already stressed and may not survive transport home. A good local fish store keeps them in dimmer, planted holding tanks and sells them in proper groups.

Online vs. Local Sourcing#

Online sellers do ship ghost catfish, but the species ships poorly. Twenty-four hours in a dark bag is hard on scaleless catfish, and arrival losses are common even with reputable shippers. A local store where you can watch the school swim, ask staff what the fish are eating, and bag them yourself produces healthier results. If you must buy online, order during mild weather, request priority shipping, and be ready to drip-acclimate the moment the box arrives.

Acclimation#

Use the drip method, not float-and-dump. Place the fish and shipping water in a clean container, then siphon tank water in at one to two drips per second using airline tubing tied off in a knot. Run the drip for 60 to 90 minutes until the volume in the container has doubled. Net the fish out (do not pour the shipping water into your tank) and release into the school. See our acclimation guide for a full walkthrough.

Quick Reference#