Jupiaba yarina

Where they come from

Jupiaba yarina is a small characin from forest streams in the western Amazon basin, showing up around blackwater and clearwater creeks with leaf litter, sandy bottoms, and good flow. Think tea-colored water, tons of tannins, and very low mineral content. They are not a common import, so most you see are wild-caught.

Setting up their tank

Give them space and clean, soft water with real current. They are fast swimmers that use the whole midwater area and look best in a tight group.

• Tank size: 90 cm/36 in long minimum (40 breeder works); 120 cm is nicer for a big group.
• Temperature: 24-28 C (75-82 F).
• pH: 5.0-6.8. They handle low 7s short term, but they relax in the acidic side.
• Hardness: soft (0-5 dGH). Keep conductivity low if you can.
• Flow: moderate to strong, high oxygen. Use a powerhead or a river-style manifold.

Substrate-wise, I like fine sand with a mix of leaf litter, a few pieces of driftwood, and some rounded stones. The leaves keep them bold and add that tea-stain they seem to switch on color in. Floating plants help break the light and calm them.

Do big, regular water changes. I do 40-60% weekly with remineralized RO to keep it soft and stable. Pre-warm and pre-condition water so you are not swinging temperature or pH.

What to feed them

They are micro-predators and can be picky at first. Wild fish usually start on moving foods and then accept prepared stuff later.

• Starter foods: live daphnia, mosquito larvae, baby brine shrimp, grindal/white worms.
• Frozen: cyclops, daphnia, mysis, finely chopped bloodworm (small pieces).
• Dry: small soft pellets or fine granules, high-protein flakes crushed down.

Once they recognize you as the food source, training to quality dry foods gets easier. Mixing a pinch of pellets with thawed frozen and letting it soak for a minute helps.

How they behave and who they get along with

They are quick, midwater schooling fish. In a group of 10+ they settle down, show better color, and spread any sparring across the group. Solo or tiny groups get skittish and nippy.

• Good tankmates: other active riverine characins, hatchetfish up top (with a lid), robust Corydoras species, small loricariids that like flow.
• Use caution: slow, long-finned fish (gouramis, angels, bettas) can get pestered by their speed and curiosity.
• Keep the pace matched: fish that enjoy current and high oxygen do best with them.

Breeding tips

They are open-water/leaf-litter scatter spawners that go at dawn, and they will eat the eggs. Spawning is doable but takes soft, very clean water and patience.

• Condition a group with lots of live and frozen foods.
• Set up a separate dim tank with soft, acidic water (pH 5.5-6.2), temp around 26-27 C.
• Use a mesh grate, marbles, or a thick leaf-litter bed so eggs drop out of reach.
• Do a slightly cooler, larger water change in the evening to trigger them; leave them overnight.
• Remove adults right after you see the morning chase and scatter.

Eggs hatch in about a day, and fry are free-swimming a few days later. Start with infusoria/green water or paramecia, then move to vinegar eels/rotifers, and finally baby brine once they can take it. Keep light low; many characin eggs are light-sensitive.

Common problems to watch for

• Jumping: any sudden movement or lights-on can launch them. Use a lid and bring room lights up before tank lights.
• Low oxygen: they hate stale water. If you see rapid gilling near the surface, increase surface agitation and check filter flow.
• Import stress and parasites: quarantine new arrivals. I routinely observe 3-4 weeks and treat for external parasites if needed. For internal worms, use a proven dewormer per directions.
• Refusing dry foods: mix tiny amounts with frozen and be patient. Overfeeding while you coax them onto pellets is the usual mistake.
• Fin nips and scuffs: they are fast and curious. Decor with sharp edges or cramped spaces leads to split fins and mouth rubs. Keep wood and rocks smooth and give them runway.
• Water quality swings: they sulk on hard, alkaline water and crash with big parameter jumps. Keep it soft and stable; large but consistent water changes work better than small, erratic ones.