Mekong sheatfish
Kryptopterus paraschilbeides
The Mekong sheatfish features a slender, transparent body with a prominent dorsal fin and elongated anal fin, displaying a pale silvery hue.
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About the Mekong sheatfish
Kryptopterus paraschilbeides is a small Mekong River sheatfish that does the whole sleek, no-dorsal-fin Kryptopterus look, but its body is more "normal catfish" than the super see-through glass catfish you usually see in shops. In the wild it moves with the flood cycle - heading into flooded forest at high water, then back to the main river seasonally - which is a pretty cool bit of behavior for a little catfish.
Also known as
Quick Facts
Size
8.3 cm SL
Temperament
Peaceful
Difficulty
Advanced
Min Tank Size
30 gallons
Lifespan
5-8 years
Origin
Southeast Asia (Mekong basin)
Diet
Carnivore/invertivore - small invertebrates, insect larvae, small fish; in aquaria use small sinking foods, frozen/live
Water Parameters
24-28°C
6-7.5
2-12 dGH
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This species needs 24-28°C in a 30 gallon tank. Use our heater calculator to find the right wattage.
Calculate heater sizeCare Notes
- Go big and go long - think 6 ft tank minimum once it starts putting on size, with strong flow and tons of oxygen. They come from moving water and get cranky in stagnant setups.
- Keep the water clean and steady: 24-28 C (75-82 F), pH around 6.5-7.5, and low nitrate (try to keep it under ~20 ppm). They do not handle big parameter swings or dirty water like tougher catfish do.
- Give them shade and current breaks - tall driftwood, rock piles, and dark areas help them settle, but leave a wide open runway for cruising. A tight lid is non-negotiable because they spook and launch.
- Feeding is easiest at dusk: sinking carnivore pellets, chopped shrimp, mussel, earthworms, and the occasional frozen foods. Target-feed with tongs or a feeding tube if tankmates outcompete them, because they can act shy and then suddenly inhale a whole mouthful.
- Tankmates need to be calm, not nippy, and too big to fit in their mouth - larger barbs/rasboras, peaceful cyprinids, and other sturdy river fish work. Avoid fin-nippers and anything small enough to become lunch, and skip aggressive cichlids that will stress them nonstop.
- Run them in a small group if your tank can handle it (3-5+), because singles stay jumpy and hidey. A group is way bolder, but you will need more filtration since they are messy eaters.
- Watch for beat-up barbels and mouth infections - sharp gravel and rough decor will shred them. Stick to sand or very smooth substrate and keep an eye out for cloudy patches or redness after scuffles or bad water days.
- Breeding in home tanks is basically a unicorn - most reports involve seasonal cues, big water changes, and lots of current, and even then they rarely go. If someone claims they bred them in a random community tank, take that with a big grain of salt.
Compatibility
Good Tankmates
- Other calm river catfish types (bigger glass catfish, peaceful shovelnose-lookalikes that stay mellow). They tend to ignore each other and just cruise the flow
- Medium-large peaceful schooling fish like larger tetras (Congo tetras) or rasboras that are too big to look like lunch. Active midwater fish help them feel secure
- Peaceful barbs that are not fin nippers (think tinfoil barbs or other larger, well-behaved barbs). They match the energy without bullying
- Chill bottom crews like larger loaches (weather loach, dojo loach, big Botia-type loaches in roomy tanks). They keep to the bottom and do not bother the sheatfish
- Sturdy, peaceful algae grazers like larger plecos or a group of SAE (true Siamese algae eaters). They coexist fine as long as everyone has space and hiding spots
Avoid
- Anything tiny that can fit in its mouth - neon-sized tetras, small rasboras, guppy sized fish. Mekong sheatfish are peaceful, but they are still predators when the lights go down
- Nippy or pushy fish - tiger barbs, some larger danios in a cramped tank, or anything that likes to test fins. This species spooks easily and does poorly when harassed
- Aggressive cichlids and territorial bruisers (oscars, convicts, most big Central American types). They will stress it out and can damage those soft whiskers and fins
Where they come from
Mekong sheatfish (Kryptopterus paraschilbeides) comes from the Mekong basin. Think big, warm, moving water - main river channels, side channels, and floodplain areas depending on season. That background explains most of their quirks: they like current, they spook easily, and they do best when the tank feels stable and predictable.
If you have kept the more common "glass catfish" (Kryptopterus vitreolus), do not assume this fish will behave the same way. This one is a different animal in size, temperament, and long-term needs.
Setting up their tank
This is an advanced fish mostly because of space and stability. You want a long footprint, not a tall show tank. They cruise, they pace, and they get stressed in tight quarters.
- Tank size: I would not bother under 180 cm (6 ft) length for adults. Bigger is easier because water stays steadier.
- Flow: moderate to strong current with calm zones. I like a river-style layout: powerheads or a strong canister return aimed down the length.
- Filtration: heavy. Big canister or sump, with lots of biological media. They are messy once they are eating well.
- Cover: dim lighting, floating plants, and big pieces of driftwood or root tangles to break line-of-sight.
- Substrate: sand or smooth fine gravel. They can scrape themselves on sharp stuff when they bolt.
- Water: warm tropical freshwater. Aim roughly mid-20s C (mid to high 70s F), neutral-ish pH, and low to moderate hardness. Stability matters more than chasing a number.
Give them "lanes" to swim through. A couple of big wood pieces arranged like a corridor does more for their confidence than a tank full of small decorations.
Keep the lights softer than you think. These fish look bold in the store, but in a bright tank they tend to hide, refuse food, or slam into glass if startled. A dark background helps a lot, too.
Tight lids are non-negotiable. If they spook, they can launch. Also cover any gaps around hoses and plumbing.
What to feed them
They are predatory and opportunistic. Mine did best on meaty foods and a routine. If you feed randomly, they stay jumpy and the shy ones lose out.
- Staples: quality sinking carnivore pellets (the kind for big catfish), fed after lights dim.
- Frozen foods: prawns/shrimp pieces, fish fillet, squid, mussel, bloodworms for smaller individuals.
- Live foods (sparingly): earthworms or blackworms can help new imports start eating. I do not rely on live feeders - too risky for disease and nutrition balance.
- How often: juveniles can take smaller meals daily; adults do well with 3-5 feedings per week depending on temperature and body condition.
Train them to a feeding spot. I used tongs to drop food in the same low-flow corner every time. Once they learn the routine, they come out much more confidently.
Go easy on fatty foods and constant heavy feeding. They will eat like pigs and then you are fighting water quality and bloated-looking fish.
How they behave and who they get along with
Expect a nervous fish that turns into a strong, purposeful cruiser once settled. They spook fast, especially during the first month. Sudden movement outside the tank, bright lights, or loud thumps can send them into panic mode.
They are also fish-eaters. If a tankmate can fit in their mouth, it is on the menu eventually. Even if you never see it happen.
- Best tankmates: larger, calm fish that can handle current and are not fin-nippy (big barbs, larger danios in very big setups, some larger peaceful cyprinids, robust loaches).
- Use caution with: cichlids that claim territory, anything hyperactive, and anything that likes to nip trailing fins.
- Avoid: small community fish, shrimp, and slow long-finned fish. Also avoid aggressive catfish that compete for the same caves/space.
Do not mix with tiny fish you are "hoping" will be fine. These are predators. You might get a peaceful month, then wake up to missing livestock.
I prefer keeping them either solo (in a huge tank) or in a small group if you can really support the bioload and space. Some individuals are more comfortable with company, but crowding them is worse than keeping one.
Breeding tips
Home breeding is not common. In the hobby, most are wild-caught or come through commercial channels, and they do not casually spawn in display tanks.
If you want to try anyway, think seasonal river fish: heavy feeding for a few weeks, then a big cool-ish water change to mimic rain, with strong flow and lots of oxygen. Even then, do not be surprised if nothing happens. If you ever get eggs, they will likely need separation because adults will not babysit them.
Honestly, most hobbyists keep this species for long-term display and behavior, not for breeding projects. If breeding is your main goal, you will have an easier time with many other catfish.
Common problems to watch for
Most issues trace back to stress, cramped space, or dirty water. These fish can look "fine" right up until they crash, so pay attention to small changes.
- Spooking and injuries: they can slam into glass or wood. Keep lighting low, give cover, and do not rearrange the tank constantly.
- Refusing food: common in new imports. Reduce light, add flow and oxygen, offer smelly frozen foods (shrimp, mussel), and keep things quiet for a week.
- Ich and external parasites: wild fish are often carrying something. Quarantine if you can. If you treat, go gentle and watch oxygen levels because medications plus warm water can drop O2 fast.
- Ammonia/nitrite sensitivity: big predatory catfish plus heavy feeding equals fast pollution. Test more than you think you need to, especially after upping food.
- Mouth damage: they can scrape their mouths on rough decor when lunging. Smooth hardscape wins.
If they are pacing the glass all day, that is usually a sign of stress or a tank that is too small/bright/bare. More cover and a longer swimming run fixes more problems than tinkering with numbers.
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