Pencil catfish

Where they come from

Ituglanis amphipotamus is one of those South American pencil catfish that feels like it was designed to test your fishkeeping patience. They come from small, often shaded streams and flooded forest areas where the water is soft, warm, and full of leaf litter and tangled roots. They spend a lot of time tucked into cover, poking around for tiny foods.

Setting up their tank

These are not a "new tank and hope" fish. I have had the best luck putting them in a mature, stable setup where microfauna and biofilm are already happening and the parameters do not swing.

Think small creeks: gentle flow, lots of hiding spots, and low stress. They are skinny little noodles and they will wedge themselves into anything that looks like a safe crack.

• Tank size: I would start at 20 gallons long for a small group. Bigger is easier because it is more stable, but footprint matters more than height.
• Substrate: fine sand is my pick. They root around and sand is kinder to their barbels.
• Hardscape: driftwood, piles of smooth stones, leaf litter, and tight caves. I like using short sections of small diameter tubing hidden under wood so they feel secure.
• Plants: not required, but floating plants or stems help keep the light dim and the fish calm.
• Filtration: clean and steady, but not a blender. Sponge filters or a canister with the output diffused works well.
• Water: soft to moderately soft is where I have seen them settle in best. Keep nitrates low and avoid big swings.

What to feed them

Feeding is the make-or-break part with these. Many arrive skinny and stressed, and they do not always recognize pellets right away. Live and frozen foods are your best tools to get them going.

• First-choice foods: live blackworms (if you can get them), live or frozen baby brine shrimp, daphnia, and cyclops.
• Reliable staples: frozen bloodworms (sparingly), chopped frozen brine shrimp, and small sinking carnivore foods once they accept them.
• Once settled: micro pellets or small sinking wafers can work, but I would not count on dry food as the only diet.

I feed after lights out or at least in low light. If you have bolder fish in the tank, target feeding helps a lot. A long pipette or turkey baster lets you drop food right at the entrances to their hides.

How they behave and who they get along with

They are quiet, secretive, and mostly nocturnal in a bright community tank. With a dim setup and a group of their own kind, they get bolder. You will still see a lot of "peek out, grab food, disappear" behavior, which is normal.

They are generally peaceful, but they are not built to compete. Fast midwater fish that smash all the food can leave your pencil cats slowly starving while looking "fine" for weeks.

• Good tankmates: calm small tetras, pencilfish, hatchetfish, small rasboras, and other gentle fish that do not hog the bottom.
• Use caution with: active bottom feeders like many Corydoras, larger loaches, and anything that piles into caves and food.
• Avoid: aggressive cichlids, large predatory fish, and fin nippers that keep them pinned in hiding.

Breeding tips

Breeding reports for Ituglanis species in home tanks are not super common, and I would call it a long-term project rather than a weekend goal. The closest I have come to spawning behavior was after a stretch of heavy feeding on live foods followed by a few cooler water changes, like a small rainy-season cue.

• Keep a group rather than a single fish. More natural interactions, and you have a chance of both sexes.
• Give them multiple tight caves and tubes. If they spawn, eggs are likely to be placed in a protected spot.
• Try seasonal signals: slightly cooler, softer water changes and increased flow for a short period can trigger activity.
• If you ever see eggs or fry, pull the adults or move the cave. They are not known for strong parental care in most setups.

Common problems to watch for

Most issues with this species trace back to two things: stress and not eating enough. They can look "normal" while losing weight, so you have to actually check body condition.

• Starvation: sunken belly, pinched look behind the head, hiding constantly. Fix by switching to live/frozen foods and target feeding.
• Sudden losses after purchase: often shipping stress plus an immature tank. A quiet, established setup and slow acclimation helps.
• Barbel wear or mouth irritation: usually rough gravel or dirty substrate. Sand and gentle maintenance make a big difference.
• Sensitivity to meds: they can react poorly to heavy dosing, especially with some copper-based treatments. If you have to medicate, go gentle and watch them closely.
• Getting trapped: they wedge into tight gaps, filter intakes, and decor. Pre-check all hardscape and use intake sponges.