Neolebias

Where they come from

Neolebias gracilis is a tiny West/Central African characin from shaded forest creeks and swamps. Think tea-colored water, leaf litter everywhere, and very gentle flow under a canopy of trees. They hug the cover and pick at tiny critters in the film on leaves and wood.

Setting up their tank

They are small, but I would still give a group their own 15-20 gallon tank. Stability helps a lot with these guys, and a longer footprint gives them room to school.

• Filtration: Air-driven sponge or a gentle HOB with a prefilter. Keep the flow mild.
• Substrate: Dark sand with leaf litter (catappa, oak, beech). Add a few small branches or roots.
• Plants: Floating plants for shade (Salvinia, frogbit). Fine plants or mosses for cover.
• Lighting: Dim to moderate. They color up better and act bolder under softer light.
• Lid: Tight-fitting. They are small and quick, and they jump.

• Temperature: 72-78 F (22-26 C)
• pH: 5.5-6.8 (they will tolerate up to ~7.0 if the water is soft and clean)
• Hardness: 1-6 dGH, low KH
• TDS: roughly 50-150 ppm

Let the tank mature a bit before adding them. They do best in tanks with stable biofilm and not much glare. Weekly 20-30% water changes with well-matched water (temp and TDS) keep them in good shape.

What to feed them

They have small mouths and a strong preference for moving food at first. Once they settle, they take good-quality micros, but live and frozen really bring out the condition.

• Staples: Baby brine shrimp, daphnia, cyclops, grindal/white worms in moderation.
• Frozen: Cyclops, daphnia, finely chopped bloodworms (tiny pieces only).
• Dry: Fine powders or nano granules (0.3-0.5 mm). Crushed high-protein flakes work if you crumble them well.

How they behave and who they get along with

In a group, they school loosely and do quick little sprints between cover. Males spar a bit and show more color, females stay a touch deeper-bodied. They are peaceful but easily outcompeted.

• Group size: 8-12+ makes them bolder and spreads any squabbles.
• Good tankmates: Small, calm fish that like the same soft water. Think tiny pencilfish, Boraras, pygmy Corydoras, small woodcats, or a quiet species-only setup.
• Fish to avoid: Anything boisterous or nippy (danios, larger barbs), or anything big enough to view them as snacks. Bright, high-flow community tanks stress them out.

Breeding

They are open/substrate scatterers and will spawn in a planted tank, but the eggs get eaten fast. If you want fry, set up a separate small tank.

• Breeding tank: 5-10 gallons, dim light, sponge filter, leaf litter or a spawning mop over marbles/mesh so eggs fall out of reach.
• Water: Soft and slightly acidic (pH ~6.0), 74-76 F. A gentle trickle of fresh, conditioned water helps trigger spawning.
• Pair or small group: Well-conditioned males and plump females. Spawning often happens at first light.
• After spawning: Remove adults. Eggs hatch in about 24-48 hours. Fry go free-swimming a few days later.

Start fry on infusoria or paramecium for the first few days, then move to vinegar eels and microworms, and finally newly hatched brine once they can handle it. Keep the tank dim and clean, with gentle aeration.

Common problems to watch for

• Jumping: Spooked fish go airborne. Secure the lid and calm the lighting.
• Feeding issues: New fish may starve in bright, busy tanks. Offer live foods and reduce competition.
• Water sensitivity: Big swings in pH/TDS or heavy hands with meds hit them hard. Match change water closely.
• Velvet/ich susceptibility: Stress can bring these on. Quarantine new fish. If you have to treat, go gentle and avoid copper with soft-water tanks.
• Bloat from dry foods: They stuff themselves. Keep portions tiny and use more live/frozen.
• Biofilm crash: Over-cleaning or over-carbon dosing can strip the tank of the micro-life they like to pick at. Clean filters lightly and avoid sterilizing the tank.