Hoplo Catfish
Megalechis thoracata
Min Tank Size
150L
Adult Size
18 cm
Lifespan
10 years
School Size
3+
About
Native to South America east of the Andes, from Trinidad down through the Amazon and Orinoco basins, the Hoplo Catfish is a member of the Callichthyidae family, making it a distant cousin of corydoras. Adults develop a thick, bony armor of scutes along their flanks, and males color up nicely with a reddish-orange tint to the pectoral fin spines during breeding season. Females tend to be a bit plainer and noticeably rounder when gravid.
Hoplos are remarkably adaptable fish. They handle a wide pH range from 6.0 to 8.0 and tolerate temperatures anywhere from 18 to 28 degrees Celsius, which means they'll coexist with a broader range of community fish than most catfish. They're also one of the few callichthyids that can gulp atmospheric air at the surface, giving them a surprising tolerance for low-oxygen conditions.
Feed them sinking pellets, frozen bloodworms, and the occasional vegetable wafer and they'll do well. Behaviorally, these are calm, unhurried fish that spend most of their time cruising the bottom and poking around in substrate or decor. They're social enough to keep in groups, but don't require it.
During breeding, males build floating bubble nests near the surface and become noticeably more territorial, so having extra space helps when that happens.
If you want to see Hoplos in actual community setups, browse the tank builds on Shimmerscape. You'll find real aquariums showing how hobbyists fit this underrated catfish into everything from South American biotopes to general community tanks with cichlids and larger tetras.
Water Parameters
Temperature
°CpH
GH
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dKHSwimming Level
Flow Preference
Keeping multiple Hoplo Catfish together
Hoplo Catfish are shoaling fish and need company of their own kind. Keep a group of at least 3. Smaller groups leave them stressed, washed-out in color, and prone to hiding.
Compatibility
Hoplos work well with medium to large South American community fish like silver dollars, larger tetras, peaceful cichlids such as angelfish or severums, and other robust catfish like plecos. They're a solid upgrade from corydoras in tanks that house bigger fish where corys would be at risk. Avoid pairing them with dwarf shrimp, small nano fish under about 4 cm, or aggressive fish that might harass a slower-moving bottom dweller. Multiple Hoplos can be kept together without much conflict outside of breeding season, though providing enough floor space and hiding spots keeps things smooth.
Commonly kept with
Species this one is most often paired withCommonly tried but avoid
Often paired, but shouldn't beCare Notes
Beginners sometimes underestimate how large Hoplos get, buying juveniles that look manageable at 6 or 7 cm and then scrambling for a bigger tank later. Plan for 18 cm and size the tank accordingly from the start. They need open surface access to gulp air, so avoid tight-fitting lids that block the entire surface or extremely turbulent flow that disrupts nest building. Substrate should be soft sand or fine gravel to protect their barbels and ventral scutes. They're hardy fish but do poorly in chronically dirty tanks, so regular gravel vacuuming is important.
Behavior & Aggression
Hoplos are genuinely peaceful under normal conditions. The one exception is during breeding, when males guard bubble nests with real determination. A male on eggs will chase off tankmates that get too close, occasionally with enough force to stress smaller fish. Outside of spawning, conspecific aggression is minimal. They don't nip fins, don't harass midwater fish, and tend to ignore everything that isn't food. The biggest risk is accidental predation on very small fish or dwarf shrimp stumbled upon at night.
Things to Know
- Males build bubble nests and guard eggs aggressively during breeding.
- Can reach 18 cm, so don't house with very small fish under 4 cm.
- Needs access to surface air, keep tank well-oxygenated with open surface.
- Can grow larger than expected, up to 15 cm.
- Will gulp air from the surface, this is normal behavior.
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