Faufré noir

Where they come from

Black brotulas are cave-loving fish from the eastern Atlantic and Mediterranean. Think rocky walls, crevices, and the twilight zones of reefs where sunlight fades. They spend daylight wedged deep in cracks, then slide out at night to hunt small crustaceans.

Setting up their tank

They do best in a dim, cool marine tank with lots of tight hides. Height is less important than floor space and rockwork. For a single fish, I like 30-40 gallons with a heavy, stable rock pile. Bigger if you want tankmates.

• Temperature: 18-22 C (64-72 F). A chiller helps in warm climates.
• Salinity: 1.025-1.026, pH 8.0-8.3, low nitrate.
• Aquascape: deep crevices, caves, and PVC pieces hidden in rock. Multiple den options.
• Substrate: fine sand with rubble pockets. They like to back into tight spots.
• Lighting: low. Blue evening lighting is fine; avoid blasting the rockwork with high PAR.
• Flow: moderate overall, but create calm zones inside caves.
• Lid: tight-fitting. Block every gap and cover overflows.

Give them time. Mine hid for a full week after going into the display. I left the lights low, fed the tank after dark, and resisted the urge to keep peeking in the cave all day.

What to feed them

They are nocturnal pickers that follow scent more than they chase. New arrivals often need live or very smelly food to get going. Start at night, right at the cave mouth.

• Live foods to start: live mysis, ghost shrimp, amphipods, blackworms.
• Frozen/silverside bits: PE mysis, finely chopped raw prawn, clam, squid, fish slivers.
• Transition trick: wiggle food on tongs at the den, or use a feeding tube to drop it in gently.
• Soak occasionally in vitamins/omega-3 (e.g., Selcon) once they are taking frozen.

Feed small amounts nightly at first. Once eating frozen reliably, every other night works. I aim for a slightly rounded belly that flattens by the next feeding. Overfeeding in a low-light tank sneaks up on you, so pull uneaten bits with a turkey baster.

How they behave and who they get along with

Quiet, secretive, and mostly active at night. They are not bullies, but they are predators. If it fits in that narrow mouth, it is on the menu after dark.

• Good tankmates: peaceful, mid-water fish that ignore caves, like larger cardinals, assessors, chromis, and mellow fairy wrasses. Also fine with larger, non-nippy gobies and blennies.
• Borderline: small dartfish and tiny gobies can become snacks. Cleaner shrimp are very risky.
• Avoid: aggressive cave-claimers (dottybacks), boisterous wrasses that pry into holes, triggers, large hawkfish, and groupers.
• With their own kind: possible in a larger tank only if you provide many cave options spaced out. Otherwise, expect cave disputes.

If you plan a community, add the brotula first, let it settle, then add calm tankmates. Feeding competition is the main headache. Target feed the brotula while the rest of the tank is busy with broadcast food.

Breeding tips

Bythitids are livebearers, and this species is reported to give birth to fully formed young. Hobby reports are rare, but a well-fed, settled pair in a cool, dim tank might drop a small brood in a cave.

• Sexing is tricky. A bonded pair will share a cave without chasing.
• Feed heavily with varied meaty foods and keep temps stable on the cooler side.
• Gestation can be months. Birth tends to happen at night.
• Newborns are relatively large. Start with newly hatched enriched brine shrimp, copepods, and tiny mysis if they will take it.
• Move the female or the fry to a quiet rearing tank with a sponge filter and lots of hiding structure.

Common problems to watch for

• Not eating: lights too bright, too much daytime activity, or food presented too far from the den. Switch to night feedings and try live mysis or ghost shrimp to kickstart the response.
• Overheating and low oxygen: they come from cooler, deeper water. Above 23 C you may see rapid gilling and listlessness. Add aeration and cool the water slowly.
• Scrapes from rockwork: they wedge hard into holes. Keep water clean and flow gentle in caves. Use quarantine if wounds look fuzzy or reddened.
• Parasites from collection: quarantine in dim light. They can be touchy with copper; I keep copper on the low end if used, or consider alternative treatments and lots of oxygenation.
• Competition: active daytime fish eat everything first. Target feed and consider dimming the tank at feeding time.
• Jumping and vanishing into overflows: run mesh lids and cover downpipes and pump intakes with guards.