Imparfinis catfish

Where they come from

Imparfinis piperatus is one of those under-the-radar little heptapterid catfish from South America. Think small tributaries and creeks with leaf litter, roots, and mixed sand-gravel bottoms. They spend a lot of time tucked into cover and come alive once the lights are low.

Setting up their tank

Give them a footprint more than height. A 20 long works for a small group, but if you can do a 30-40 gallon breeder style tank, it makes life easier for both you and the fish. They like to cruise the bottom edges and shoot between hiding spots.

Substrate matters. I have had the best luck with sand or very smooth fine gravel. Sharp gravel can beat up their barbels over time, especially if you are a little heavy-handed with feeding and they are constantly rooting around.

• Substrate: sand or smooth fine gravel
• Hardscape: driftwood, tangled roots, rock piles with stable gaps
• Cover: leaf litter (catappa/oak/beech), clumps of plants, floating plants to dim the light
• Flow: moderate, with calmer pockets behind wood and rocks
• Filtration: a filter that moves water but does not blast the bottom (sponge prefilter helps)

For water, aim for clean and stable. Soft-to-medium water is fine, slightly acidic to neutral is easy mode, and warmish temps work well. They are not a fish I would stick in a brand new tank. They handle normal maintenance just fine, but they do not love big swings.

What to feed them

These are not algae eaters. They are little predators and scavengers, and they do best with meaty foods. If you only feed flakes at the surface, you will wonder why they look thin. Feed with the lights dim or right after lights-out and you will see a totally different fish.

• Staples: sinking carnivore pellets, wafer-style bottom foods with high protein
• Frozen: bloodworms, blackworms, daphnia, brine shrimp, chopped mysis
• Live (treat): blackworms, live baby brine, mosquito larvae where safe/legal
• Occasional: finely chopped earthworm (small pieces, not a whole worm flopping around)

Watch their bellies. A well-fed Imparfinis has a gently rounded belly after meals, not a pinched look behind the head. If you keep a group, spread food to a couple of spots so the bold one does not dominate.

How they behave and who they get along with

They are mostly peaceful, a little skittish, and very nocturnal-leaning. In a bare tank they vanish. In a tank with wood, leaves, and dim areas, they start doing that confident catfish cruising along the bottom and popping out to grab food.

They do fine solo, but I like them in small groups if the tank is big enough. You will see more natural behavior, and they seem less jumpy. Just give them enough hidey-holes so nobody has to fight over the best spot.

• Good tankmates: small-to-medium tetras, pencilfish, hatchetfish, rasboras, peaceful dwarf cichlids, Corydoras (if there is enough bottom space)
• Use caution: very boisterous barbs or big rainbowfish that outcompete them at feeding time
• Avoid: aggressive cichlids, big predatory catfish, anything that can swallow them, and shrimp you are attached to

Breeding tips

Breeding Imparfinis piperatus in the average home tank is not something you see all the time. They do not behave like the common spawning catfish people are used to (like Corydoras), and a lot of pairs just never tip over into spawning without specific triggers.

That said, if you want to try, think rainy season. Heavy feeding on live/frozen foods for a couple weeks, then a few days of slightly cooler, larger water changes with good oxygenation and flow. More hiding spots and darker conditions help them feel secure enough to do anything interesting.

• Start with a group (not just two) so you likely have both sexes
• Condition with meaty foods and stable warm temps
• Trigger attempts: cooler water change, increased flow, extra aeration
• Give spawning sites: tight caves, leaf piles, dense root tangles

Common problems to watch for

Most issues I have seen come down to three things: stress from bright/open tanks, being outcompeted for food, and dirty substrate pockets. They are hardy enough once settled, but they do not love neglect.

• Barbel wear: usually from sharp gravel or filthy substrate. Switch to sand and keep the bottom clean.
• Skin irritation or fin damage: often from being shoved around by aggressive tankmates or from poor water quality.
• Hiding nonstop: too much light, not enough cover, or they feel exposed. Add wood, leaves, floaters, and break lines of sight.
• Getting skinny: food is not reaching them. Feed after lights-out and use sinking foods or target feeding.
• Jumping: gaps in the lid. Seal openings and keep the water line a bit lower.

If you set them up with cover, keep the bottom from getting gross, and make sure they actually get dinner, they are a really rewarding oddball catfish. The first time you catch them confidently prowling at dusk, you will get why people get hooked on these lesser-known species.