no established common name

Where they come from

Aphanotorulus phrixosoma is a rare loricariid from northern South America. Think warm, moving water with sandy stretches, wood piles, and leaf litter. They hug the bottom, dart between logs, and graze on whatever grows there. Most show up as wild-caught fish, and they are often mixed in with similar-looking plecos.

Setting up their tank

Plan for a big footprint and strong flow. They are active after dark and need room to cruise and multiple places to feel secure. Wood is not optional here.

• Tank size: 75 gallons is the practical starting point for a single adult. For a pair or with other bottom fish, 120+ gallons with a 48-72 inch length works much better.
• Footprint: prioritize length and width over height. They like to run, not climb.
• Filtration and flow: big canister plus a powerhead or river manifold. Aim for brisk, well-oxygenated water. A spray bar or rippled surface 24/7.
• Temperature: 25-28 C (77-82 F).
• pH and hardness: pH 6.2-7.4, soft to moderate hardness (2-12 dGH). Stability beats chasing numbers.
• Substrate: fine sand or smooth small gravel. They sift and shove it around.
• Decor: multiple chunks of real driftwood (mopani, bogwood, spider wood) plus rock piles and a few snug caves (PVC capped on one end works).
• Lighting: dim. Use floating plants or wood to break up light. They relax more and come out earlier.
• Lids: tight. They are strong and can wedge upward during night patrols.

What to feed them

They are heavy grazers that rasp wood and biofilm. Think fiber-first diet with some greens and occasional protein. If you only feed meaty pellets, they get fat inside and still look hungry.

• Daily base: high-quality sinking wafers or gel food with lots of plant matter and fiber.
• Wood fiber: keep real driftwood in the tank. They work at it nightly.
• Veggies: zucchini, cucumber, blanched green beans, squash. Weight it down. Remove leftovers in the morning.
• Protein 2-3x weekly: small portions of frozen mysis, brine, or a shrimp pellet. Keep it modest.
• Bonus graze: leaf litter (dried Indian almond, oak) for biofilm and microfauna.

How they behave and who they get along with

Mostly nocturnal. They are busy but not hyper, and they pick a few favorite routes between wood piles and caves. With their own kind or similar-shaped plecos, they can be territorial, especially at feeding time or over caves.

• Good tankmates: midwater characins, peaceful cichlids that are not cave-obsessed, robust tetras, hatchetfish, and surface fish that do not compete on the bottom.
• Use caution: other large loricariids. It can work in a big tank if each has defined space and multiple feeding spots.
• Avoid: fin-nippers, hyper-aggressive cichlids, or tiny shrimp that will get bulldozed.

Breeding tips

This species is rarely spawned in home aquaria. They are cave spawners with the male guarding the clutch. You need room, steady conditioning, and very clean, well-oxygenated water. Expect months of prep, not a weekend project.

• Sexing: mature males usually develop more cheek and pectoral odontodes and a broader head. Females carry more mass behind the pectorals.
• Layout: several snug caves with only one entrance, different widths. Place them facing into the current and near wood.
• Conditioning: heavy on fiber and veg with small, regular protein. Keep nitrates low with frequent water changes.
• Triggers: simulate rainy season with a week of cooler (by 1-2 C) soft water changes and slightly stronger flow.
• After spawning: keep current up. The male will fan. Protect the cave from nosy tankmates. Have a fry saver or sponge-covered intake ready.
• Fry: start with biofilm, blanched veg slivers, and powdered wafers. Keep wood available from day one.

Common problems to watch for

• Low oxygen: rapid gill movement, hugging the output, and daytime gasping. Add air and flow right away.
• Internal parasites from wild fish: eating well but losing weight, pale stringy poop. Quarantine and treat appropriately after a firm ID.
• Bloat from rich foods: swollen belly, lethargy. Cut protein, add greens and wood, and increase water changes.
• Territorial scuffs: split fins and scrape marks after cave disputes. Add more caves and visual breaks.
• Filter clogging: wood rasping makes fine sawdust. Rinse mechanical media often or add a prefilter sponge.
• Stress from bright light: hiding 24/7 and not feeding. Dim the tank and add floaters or more wood cover.