Glass Catfish Care Guide: Tank Size, Diet, Water Parameters and Temperament

Glass catfish look like living X-rays, and that alone sells a lot of them — but their transparent bodies hide a fish that is far less forgiving than its small size and gentle nature suggest. This guide walks through exactly which fish you're buying, the tank size and water chemistry it needs to thrive, and the mistakes that most often kill it early.

What Is a Glass Catfish, Really?

The name "glass catfish" gets applied loosely, and that confusion is the single biggest reason people set these fish up wrong. Here's the untangling:

• Glass catfish / ghost catfish (Kryptopterus vitreolus) — this is the fish almost everyone means and almost everyone sells. For decades it was mislabeled Kryptopterus bicirrhis in the trade, which is a naming error you'll still see repeated online.
• True ghost catfish (Kryptopterus bicirrhis) — a separate, rarely traded species. It's mostly opaque or white, with only the head showing any transparency. If a "ghost catfish" you're looking at isn't see-through, it's likely this species, not the common glass catfish.
• Kryptopterus minor (dwarf glass catfish) — a smaller, less common relative topping out around 2.5 inches (6 cm), kept the same way as K. vitreolus but scaled down.
• Glass fish / painted glass fish / Indian glass fish (Parambassis ranga) — not a catfish at all. This is a perch-like species, frequently sold dyed in neon colors ("painted"), which is a different animal with different needs (covered below).

For the rest of this guide, "glass catfish" refers to Kryptopterus vitreolus, the transparent, barbeled catfish most commonly sold under that name.

Appearance

The defining feature is a fully transparent body that lets you see the skeleton, spine, and internal organs. Other identifying traits:

• No dorsal fin
• A forked tail that's nearly invisible against the body
• Forward-facing barbels used to feel around in low light
• Large, reflective eyes
• A slim, laterally compressed profile built for open-water schooling

Size and Lifespan

Adult glass catfish typically reach 3–4 inches (7.5–10 cm), with some individuals stretching toward 5–6 inches (12.5–15 cm) in older reports. Those larger figures likely reflect confusion with other Kryptopterus species rather than typical K. vitreolus growth, so plan around the 3–4 inch range and treat anything larger as a bonus.

Lifespan runs 5–8 years with consistent care, though sources vary — some report as little as 5 years, others 7–8. The deciding factor isn't genetics; it's how stable the water stays over the fish's life.

Tank Size and Setup

Minimum Tank Size

A 30-gallon (113 L) tank is the realistic minimum for a school of 5–6 glass catfish. Some care sheets frame the requirement as tank length instead of volume, suggesting roughly 40 inches (100 cm) of length rather than a gallon figure — and for a schooling, mid-water swimmer, footprint really does matter more than pure volume. A long, low 30-gallon gives the school room to move as a group in a way a tall, narrow tank of the same volume doesn't.

Bigger is genuinely easier here: a larger volume of water resists the temperature and chemistry swings that this species can't tolerate.

Stocking math: a 30-gallon long tank comfortably suits a school of 6 glass catfish alone. If you want to add a modest peaceful community around them (a few corydoras, a group of small tetras), plan on stepping up to 40 gallons (150 L) or more so the school isn't competing with tankmates for stable water quality and swimming space.

Substrate, Lighting, and Decor

Element	Recommendation	Why
Substrate	Fine sand or smooth small gravel	Sharp or coarse gravel damages sensitive barbels, inviting infection
Lighting	Dim to subdued	This species relies on camouflage and blends poorly under bright light, which increases stress
Plants	Java fern, java moss, hornwort, floating plants	Provide shade and a sense of security without blocking the open water column
Hardscape	Driftwood pieces	Adds cover and diffuses light without turning the tank into a maze
Water column	Keep the middle to upper zone open	Glass catfish are not bottom dwellers — they school in open water, not among decor

A densely planted tank with a genuinely open swimming lane in the middle is the combination that gets a shy species to actually come out and school where you can see it.

Water Parameters

Water chemistry is the make-or-break variable for this fish — more than tank size, more than diet, more than tankmates. Every reliable source repeats the same theme: the exact number matters less than how stable it stays.

Parameter	Target Range
Temperature	75–80°F (24–27°C), aim for ~77°F (25°C)
pH	6.5–7.0 (soft, slightly acidic)
General/carbonate hardness	Roughly 8–12 dGH/dKH (soft to moderate)
Water flow	Low to moderate

Glass catfish come from slow-moving, shaded jungle streams, which explains both the low-flow preference and the sensitivity to sudden change. A tank that swings from 74°F to 82°F overnight is more dangerous to this fish than one that sits steadily at 79°F.

Only add glass catfish to a tank that has been fully cycled for at least 4 weeks. This is one of the least forgiving common community species when it comes to ammonia and nitrite — it should never be part of a fishless-cycling shortcut or a week-one stocking plan.

Avoiding Parameter Swings

Since instability, not any single bad number, is the top cause of sudden deaths in this species:

• Do smaller, more frequent partial water changes (10–15% weekly) rather than large, infrequent ones.
• Match the temperature of new water to the tank before adding it.
• Test parameters after any equipment change, not just when the fish look off.
• Keep a reliable heater and thermometer running at all times — a $10 sensor failure can undo months of stable care.

Diet and Feeding

Glass catfish are carnivorous-leaning omnivores with small mouths, so food particle size matters as much as food type.

• Staples: live or frozen bloodworms, brine shrimp, daphnia, tubifex, and mosquito larvae.
• Secondary: high-quality flake or pellet food sized for a small mouth, once the fish is established.

Sources disagree on how central flake food should be. Some describe glass catfish as needing to "learn" to accept dry food and staying primarily live/frozen feeders; others treat flake as an easy staple from the start. The safer approach for new stock: start newly introduced fish on live or frozen foods to make sure they're actually eating, then gradually work in flake or pellet once the fish is confidently feeding, usually after the first couple of weeks.

Feed once or twice daily, offering only what the school clears in a couple of minutes. Overfeeding in a tank that's already parameter-sensitive compounds water quality problems fast.

Temperament and Tank Mates

Glass catfish are peaceful, shy, and skittish — not fin-nippers, not aggressors. New arrivals typically hide for 2–3 weeks before settling in and swimming confidently in open water. That initial hiding is normal, not a red flag on its own.

The Schooling Requirement

This is repeated across every source as the single most important welfare factor: keep glass catfish in groups of 5–6 minimum, ideally more. A lone fish, or even a pair, becomes visibly stressed, hides constantly, and often dies well before its expected lifespan. Never buy fewer than 5.

Good and Bad Tank Mates

Compatible:

• Small tetras (neon, cardinal, glowlight)
• Rasboras
• Corydoras
• Kuhli loach
• Otocinclus
• Small livebearers (mollies, swordtails)
• Dwarf gouramis

Avoid:

• Barbs, cichlids, oscars, and other boisterous or aggressive fish that outcompete glass catfish at feeding time and stress a species that's already easily unsettled

You can browse suitable community options in FishyHub's small community fish selection or check corydoras as an easy bottom-dwelling companion.

Species You Might Confuse With Glass Catfish

Because "glass" gets used loosely as a common name, a few unrelated fish get mixed up with the true glass catfish at the point of sale.

Painted Glass Fish (Parambassis ranga)

Not a catfish — a perch-like glassfish species, often sold artificially dyed in bright colors ("painted"). It's carnivorous and, particularly after the dyeing process, prone to disease and lymphocystis as well as ich. It needs a similarly densely vegetated, still-water setup, but it is a genetically and behaviorally different fish from Kryptopterus vitreolus.

Indian Glass Fish (Parambassis ranga)

The undyed, natural-color version of the same species above, sometimes marketed as "glassy fish." It reaches about 2.5–3 inches (6–7.5 cm), lives 3–5 years, and should also be kept in schools of 6 or more. It needs regular partial water changes on roughly a monthly to biweekly schedule.

Kryptopterus minor

A genuine dwarf relative of the true glass catfish, maxing out around 2.5 inches (6 cm) and rare in the trade. Care requirements mirror the standard glass catfish, just scaled to a smaller tank footprint.

Common Mistakes to Avoid

• Buying only 1–2 fish — guarantees stress, hiding, and early death. Buy 5–6 or more at once.
• Letting temperature or pH swing during water changes — the top cause of sudden deaths in this species. Match temperature and change smaller volumes more often.
• Using sharp gravel — damages barbels and invites secondary infection.
• Skipping quarantine — introduces disease into an already sensitive tank.
• Offering only dry flake to a newly added fish — a fish that won't eat flake yet can starve. Start with live or frozen food.
• Mixing with fast or aggressive tankmates — leads to chronic stress and faster disease onset.
• Overly bright lighting or a bare tank — keeps the fish hidden and stressed instead of schooling openly.
• Assuming this is a beginner fish — the real challenge is water stability, not aggression or size. Rate the species moderate/intermediate difficulty.

Quarantine and Acclimation

Given how quickly this species reacts to poor water conditions, don't skip the basics.

Quarantine

New fish — and new plants — should spend 2–4 weeks in a separate quarantine tank before joining the display, giving you time to spot ich or other parasites before they reach the main school.

Drip Acclimation

Because glass catfish are especially sensitive to abrupt parameter changes, drip acclimation is worth the extra time over a quick float-and-dump:

1. Float the sealed bag in the tank for 15–20 minutes to equalize temperature.
2. Open the bag and begin drip acclimation, adding tank water at roughly 2–4 drops per second.
3. Continue for 30–60+ minutes until the volume has roughly doubled.
4. Keep tank lights off during the process to reduce stress.

If you're buying online, this extra acclimation time matters even more — mail-order shipping is itself a parameter shock, so buying locally when a good specimen is available is a reasonable way to reduce that stress for such a sensitive species.

Basic Equipment Checklist

Because tolerance for parameter drift is so narrow, reliable equipment isn't optional for this fish:

• A heater capable of holding a steady temperature
• An accurate thermometer (don't rely on the heater's dial alone)
• A filter sized appropriately for a 30-gallon-plus tank with gentle output
• A liquid test kit for ammonia, nitrite, nitrate, and pH
• A quarantine tank set up before you buy

Buying Readiness Checklist

Before bringing glass catfish home, confirm:

• Your display tank has been fully cycled for at least 4 weeks
• Heater and thermometer are installed and verified accurate
• You're prepared to buy a group of 6 or more, not fewer
• A quarantine tank is ready to receive new stock

Breeding

Breeding glass catfish in a home aquarium is rare and difficult, not a realistic beginner or intermediate project. In the wild, spawning is tied to seasonal rains and cooler, fresher water conditions. Sexing the fish externally is very difficult, eggs are scattered on plants and hatch within a few days, and fry require infusoria followed by baby brine shrimp to survive. Treat any successful breeding as an advanced, uncommon outcome rather than something to plan around.

Health and Disease

There's no disease unique to glass catfish, but they react to poor water quality faster than hardier community fish. Watch for:

• Ich (white spot disease) — visible white specks on the body and fins
• Fin or tail fungus — often follows stress or minor injury
• Flashing or scratching — a sign of irritation, sometimes from parasites, sometimes from water quality alone

Prevention comes down to the same fundamentals repeated throughout this guide: stable parameters, regular partial water changes, quarantining new stock, and avoiding overstocking.

Frequently Asked Questions

Are glass catfish easy to keep?

No. They're peaceful and small, which makes them look beginner-friendly, but they demand tightly stable water chemistry that punishes mistakes quickly. Rate them moderate to intermediate difficulty, not a true beginner fish.

How many glass catfish should I keep together?

Keep a minimum of 5–6, and more is better. Never keep fewer than 5 — a lone or paired fish becomes stressed, hides constantly, and often dies early.

What's the difference between glass catfish and ghost catfish?

In most cases, none — "ghost catfish" is just an alternate common name for Kryptopterus vitreolus, the same fish sold as "glass catfish." The true Kryptopterus bicirrhis is a separate, mostly opaque species that's rarely traded, so don't assume every "ghost catfish" listing is that rare fish.

Do glass catfish eat other fish or shrimp?

Generally not adult fish or adult shrimp, since their mouths are too small. They may pick off very small fry or baby shrimp, so don't expect them to be fully safe with a breeding shrimp colony.

Can glass catfish live with bettas or shrimp?

They're compatible with peaceful, shrimp-safe community fish, and adult shrimp are generally safe around them. Bettas are hit-or-miss depending on the individual betta's temperament, so proceed cautiously and watch closely after introduction.

Why is my glass catfish hiding all the time?

Hiding for the first 2–3 weeks after introduction is normal. If it persists beyond that, check that the school has enough members (5–6+), that the tank offers shade and plant cover, and that water parameters are stable — persistent hiding afterward usually points to stress rather than a settling-in period.

Why did my glass catfish suddenly die?

The most common cause is a water parameter swing — a temperature shift or an ammonia/nitrite spike — rather than disease. Test your water immediately if a fish dies without obvious symptoms.

Can glass catfish breed in a home aquarium?

It's extremely rare and difficult, and not reliably documented among home hobbyists. Treat it as an advanced, unlikely project rather than something to plan a tank around.

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Once your water parameters and school size are sorted, you can browse available stock in FishyHub's freshwater livestock section to find glass catfish and suitable tank mates for a calm, well-planted community setup.