Chinese large-mouth catfish

Where they come from

Chinese large-mouth catfish (Silurus meridionalis) are big, nocturnal predators from southern China. You find them in broad rivers, connected lakes, and deep, silty backwaters of the Yangtze and nearby drainages. They like slow to moderate flow, dim water, and places to hole up during the day. They are also farmed for food in parts of China, which is why you sometimes see them offered to hobbyists.

Tank setup

Plan for the adult from day one. A fast-growing juvenile will blow past 30-40 cm before you know it. My rule: if you cannot house an adult, skip the species.

• Footprint and size: aim for at least 8 x 4 ft (2.4 x 1.2 m) footprint and 600-1,000+ gallons for an adult. Bigger is better. Short, wide tanks or indoor ponds beat tall tanks.
• Cover and security: tight, weighted lids with no gaps. They spook hard and jump. Dim lighting. A red night light lets you watch feeding without stressing them.
• Hides: big-diameter PVC or smooth logs at least 1.5x the fish's body width. Anchor them so the catfish cannot roll them.
• Substrate: bare bottom for easy cleaning, or a thin layer of rounded sand. Skip sharp gravel.
• Filtration: heavy duty. Think large sump with oversized mechanical prefilters (filter socks, sponges) plus a mountain of bio-media. 6-10x hourly turnover and lots of aeration.
• Flow and oxygen: moderate flow with strong surface agitation. Add backup air (battery air pump) if power blips are common.
• Heating and safety: use an external or guarded heater. These fish burn themselves on exposed heaters and smash glass equipment.
• Water parameters: pH 6.5-7.8, soft to medium hardness. Temperature 18-26 C (64-79 F). Keep it toward the cooler end if you want a calmer metabolism and better oxygen.

Water changes matter more than chasing perfect numbers. I run 30-50% weekly on a mature system and vacuum up leftovers the morning after heavy feeds.

Feeding

They are pure predators with a great sense of smell. They take to prepared foods if you stick with it. I feed after lights out or under red light so they feel bolder.

• Staples: sinking carnivore sticks/pellets, chopped tilapia, catfish fillet, shrimp, mussels, nightcrawlers. Rotate items and add a vitamin soak once or twice a week.
• Training: start with meaty foods for scent, then mix in pellets. Gradually shift the ratio toward pellets.
• What to skip: feeder goldfish/rosies (parasites and thiaminase), very fatty meats, and spiny fish that could lodge in the throat.
• Schedule: juveniles daily in small portions; subadults every other day; big adults 2-3 times per week. Less is usually better than more with these guys.
• Technique: use tongs. They strike hard and you do not want fingers near that mouth. Remove leftovers within 15 minutes.

Behavior and tankmates

Think quiet, ambush hunter. By day they loaf in a hide; at night they cruise and inhale anything that fits. They are not mean for the sake of it, but they are built to eat fish.

• Best plan: species-only in a big, simple layout.
• If you try tankmates: only very large, robust fish that are too deep-bodied to be swallowed. Even then, there is always risk.
• Avoid: spiny plecos and catfish (pectoral spines can lock in the throat), nippy fish that harass barbels, and anything under half the sheatfish's body length.
• Lights: keep it dim and give multiple hides to lower startle responses and reduce collisions.

Breeding

Home breeding is rare. In the wild and in ponds, Silurus species spawn in warm season, laying adhesive eggs in nests or cavities, with the male guarding. In aquaculture, this species is often hormone-induced to spawn.

• What it would take: a very large, quiet indoor pond with seasonal cues (cool winter, warming spring), big caves or brushy nest sites, and a compatible pair.
• Eggs and fry: eggs stick to surfaces; male may guard. Fry start on small live foods and need immaculate, well-oxygenated water.
• Reality check: pairing, aggression, and sheer space needs put this outside the normal hobby. Most specimens are not sexed and may never pair.

Common problems to watch for

• Ammonia and nitrite spikes: heavy feeding overwhelms filtration. Use big prefilters and do not overfeed.
• Low oxygen: warm water and big biomass can outstrip O2. Run strong aeration, especially after feeds and during heat waves.
• Injuries from panic runs: add soft decor edges, secure hides, and keep lighting gentle. Treat scrapes quickly to prevent infections.
• Internal issues from poor diet: too many fatty or thiaminase-rich foods lead to problems. Keep variety and use vitamin soaks.
• Parasites from feeders: avoid or quarantine feeders. Deworm new arrivals proactively if you have the know-how.
• Medication sensitivity: as a scaleless catfish, it can react badly to copper and strong dyes. If you medicate, start at reduced dose, boost aeration, and watch closely.
• Heater burns and equipment strikes: use heater guards or external heaters and shield pump intakes so barbels do not get sucked in.