Brachyhypopomus batesi

Where they come from

Brachyhypopomus batesi is a small South American electric knifefish from slow, warm floodplain waters. Think quiet Amazon-side creeks, flooded forests, and leaf-choked margins with soft, tea-colored water. They spend a lot of time tucked into roots and leaf litter, pulsing away with their little electric organ.

Setting up their tank

These guys are advanced because they want very stable, soft, low-conductivity water and a calm, shadowy tank. Give them space to cruise and lots of cover to disappear into.

• Tank size: for one, a 36 in/90 cm long tank (30-40 gal) is the bare minimum; 55 gal+ is nicer. Length matters more than height.
• Substrate: fine sand. They rub along the bottom and can scrape up on gravel.
• Cover: piles of leaf litter (catappa/oak), driftwood tangles, PVC tubes, and dense plants or mossy mops. Floating plants to mute the light.
• Filtration: oversized sponge filter or canister with gentle return. Pre-filter any intakes with a foam sleeve so they do not ding their snout.
• Flow and oxygen: gentle current with good gas exchange. Aim the outlet along the surface rather than blasting the bottom.
• Lighting: dim. They relax under subdued light; a red flashlight works great for viewing at night.
• Lid: tight-fitting. They can and will launch themselves through tiny gaps.
• Water: warm, soft, slightly acidic. Shoot for 76-82 F (24-28 C), pH 5.5-7.0, GH/KH low, conductivity under ~200 uS if you can manage it.

What to feed them

They are nocturnal micro-predators. Mine ignored flakes and most pellets at first. Start with live or high-quality frozen foods, then you can try to wean.

• Go-to foods: live blackworms, chopped earthworms, mosquito larvae, daphnia, bloodworms, small mysis or brine shrimp (rinsed).
• Target feeding: use tongs or a turkey baster to place food right by their hide after lights out.
• Routine: small portions 5-6 nights a week. Their guts are not built for big, infrequent meals.
• Supplements: once a week I dust thawed foods with a vitamin prep to cover gaps.

How they behave and who they get along with

Calm, secretive, and most active after dark. They are not bullies, but they do spook easily and rely on their electric sense to find food and navigate.

• Best kept: singly in a quiet community, or as a small group only in a big, heavily structured tank. Same-species squabbles are usually posturing but watch for nipped tails.
• Tankmates: small, peaceful fish that ignore them. Think pencilfish, hatchetfish, sedate tetras, or Corydoras. Avoid fin-nippers and anything big enough to try a bite.
• Avoid: other electric fish (elephantnoses, black ghosts, Gymnotus) because their signals can interfere and stress everyone.
• Feeding competition: pick tankmates that do not vacuum every scrap. You will be feeding after lights out, so boisterous day-feeders are fine as long as they sleep at night.

Breeding tips

This genus has been bred in labs and occasionally by advanced hobbyists, but it is not common in home tanks. They are seasonal spawners tied to rainy-season cues.

• Set up a species tank with very soft, acidic water, leaf litter, and a thicket of roots or spawning mops near the surface and bottom.
• Condition a pair or small group heavily on live foods.
• Simulate seasons: a week of slightly cooler, large water changes with very soft water, then a gradual warm-up with longer photoperiod.
• Courtship is subtle. Eggs are usually laid on or among vegetation or roots; reports suggest some male attendance, but do not count on it.
• If you spot eggs, reduce flow, keep it dim, and consider moving adults out. Fry will need infusoria/Paramecium at first, then freshly hatched baby brine and microworms.

Common problems to watch for

• Refusal to feed: usually stress from light, flow, or pushy tankmates. Fix the environment first, then try live foods and night feedings.
• Snout and belly scrapes: happen on rough decor or intake strainers. Use sand and foam pre-filters, and keep wood edges smooth.
• Jamming stress: mixing with other electric species (or too many conspecifics in tight quarters) leads to constant signal adjustment and poor appetite.
• Medication sensitivity: copper, formalin, and malachite green can hit them hard. Quarantine new fish so you are not forced into tank-wide treatments.
• Water quality crashes: leaf litter is fine, but do not let it rot into sludge. Vacuum lightly and replace leaves in batches.
• Jumping: spooks lead to launches. Keep a snug lid and dim the room lights before tank lights switch on or off to avoid startle jumps.