Jupiaba apenima

Where they come from

Jupiaba apenima is a small, lively characin from clear-water forest streams in the eastern Amazon of Brazil. Think sun-dappled creeks with sand and fine gravel, leaf litter, and steady flow. They spend their time midwater picking off tiny invertebrates and drifting bits of food.

Setting up their tank

Give them swimming room and good oxygenation. A 30-inch/75 cm long tank (around 20-30 gallons) is a comfortable start for a group. They are fast and active, so length matters more than height.

• Group size: 10+ fish settles them down and spreads any nippy behavior.
• Temperature: 75-82 F (24-28 C).
• pH: ~5.5-7.2. Slightly acidic to neutral works well.
• Hardness: 1-8 dGH. They appreciate soft water, but moderate is usually fine if stable.
• Flow: moderate, steady current with high oxygen.

Use sand or fine gravel, a few smooth stones, and a tangle of wood or roots. Leaf litter (catappa or oak) is great for tannins and microfauna. Plants are optional, but hardy, flow-tolerant species like vallisneria or bolbitis look good and give cover.

Filtration should be robust but not a vortex. A canister or HOB with a spray bar, plus an airstone or small powerhead, keeps the water moving and well oxygenated. They come from clean water, so stay on top of maintenance.

• Lighting: moderate and a bit subdued. Floating plants help.
• Water changes: 30-50% weekly keeps them looking sharp.
• Cover: tight lid. They are jumpers, especially at lights-on and during spooks.

What to feed them

They are micro-predators in the wild. In the tank, keep portions small and varied to bring out color and condition without bloating them.

• Daily staple: quality fine flakes or 0.5-1 mm micro pellets.
• Frozen: daphnia, cyclops, baby brine shrimp, bloodworms (in moderation).
• Live treats: baby brine shrimp, grindal worms, mosquito larvae where legal.
• Occasional veggie: spirulina flake to balance richer foods.

How they behave and who they get along with

Think of them like a slightly feistier tetra. In a proper group they school nicely and spend most time midwater, flashing around in the current. Too few fish and they can redirect that energy into fin-nipping.

• Good tankmates: other mid-sized, quick characins; hatchetfish up top; Corydoras and small Loricariids on the bottom; peaceful dwarf cichlids that are not overly territorial.
• Avoid: slow or long-finned fish (bettas, guppies with big tails, fancy angels); shrimp colonies unless heavily planted; very aggressive cichlids.

Breeding tips

They are classic egg scatterers with no parental care. Spawns are doable if you set up a dedicated tank and keep the adults well fed beforehand.

• Condition a group with frozen/live foods for 1-2 weeks.
• Breeding tank: 10-15 gallons, bare bottom, mesh or marbles, plus fine-leaved plants or yarn mops.
• Water: soft and slightly acidic (pH 6.0-6.6), 77-79 F (25-26 C), very clean with gentle flow and dim light.
• Introduce 1-2 females with 2-3 males in the evening.
• They usually scatter eggs at first light. Remove adults right after.
• Incubation: about 24-36 hours. Free-swimming by day 3-4.
• First foods: infusoria or commercial liquid fry food, then microworms and newly hatched brine shrimp.

Common problems to watch for

• Jumping: they spook fast. Keep a snug lid and break up reflections at the surface.
• Low numbers = nipping: understocked groups get pushy. Bump the school to 10-15.
• Oxygen dips: warm water and low surface movement can make them gasp. Add an airstone or increase surface agitation.
• Rich diets: too much bloodworm or big pellets can cause bloat. Mix in daphnia and fiber-rich foods.
• Post-import ich or velvet: quarantine new fish 2-4 weeks and treat early if you see flashing or white spots.
• Fin wear: usually from squabbles in small groups or cramped quarters. More space and more fish in the school fixes most of it.