Doce River moenkhausia (lambari)
Moenkhausia doceana
Also known as: lambari, piaba
Moenkhausia doceana is a Brazilian characin from the Doce and Mucuri river basins - basically a regional "lambari" type tetra. In the wild it hangs in the water column of clear, moving streams and picks off insect larvae and other little buggy bits, so it tends to do best in a roomy tank with good flow and a group of its own kind.
Moenkhausia doceana features a streamlined body, distinctive silver coloration, and a prominent black spot at the base of the caudal fin.
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Quick Facts
Size
7.7 cm SL
Temperament
Peaceful
Difficulty
Intermediate
Min Tank Size
30 gallons
Lifespan
4-8 years
Origin
South America (eastern Brazil - Mata Atlantica coastal drainages)
Diet
Carnivore/invertivore - quality flakes/pellets plus frozen/live foods (insect larvae, small crustaceans)
Water Parameters
22-26°C
6-7.5
2-12 dGH
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Calculate heater sizeCare Notes
- Keep them in a real group (8-12+). In small numbers they get nippy and you will see the weakest fish get chased nonstop.
- Give them open swimming room with plants or wood around the edges so they can duck out of sight. A 20-30 gallon long footprint works way better than a tall tank for this fish.
- They do fine in typical soft-to-neutral community water: aim around 72-79F, pH roughly 6.2-7.5, and keep nitrates low with weekly water changes. They show better color and less fin drama when the water is clean and the current is moderate.
- Feed small foods they can grab fast: good flake or micro-pellets daily, plus frozen daphnia, cyclops, or brine shrimp a few times a week. Split it into 2 smaller feedings if you can, because they are pigs and the shy ones miss out.
- Tankmates: other quick, non-finny fish like other characins, rasboras, danios, and peaceful bottom fish like corys. Skip slow long-finned stuff (bettas, fancy guppies, angelfish) unless you want shredded fins.
- Use a tight lid - they will jump when spooked or during feeding. Also cover filter intakes, since curious juveniles can get pinned on strong suction.
- Breeding is doable if you give them a separate tank with a mesh or marbles on the bottom and lots of fine-leaf plants; they scatter eggs and will eat them. Condition with live/frozen foods, then pull the adults after a spawn and raise fry on infusoria or powdered fry food, moving to baby brine shrimp once they can take it.
Compatibility
Good Tankmates
- Other medium-small South American tetras that stay chill in a school (black neon tetra, bloodfin, lemon tetra). Lambari are pretty social and do best when everyone is there to just cruise and shoal.
- Corydoras catfish (any of the common species). They stick to the bottom, dont bother the lambari, and they handle the same general water and feeding routine.
- Small to medium peaceful Loricariids like bristlenose plecos or smaller Hypancistrus. They mind their own business and dont compete in the midwater where the lambari hang out.
- Hatchetfish (marbled or silver) if you have a tight lid. Different zone, similar vibe, and they are not pushy.
- Dwarf cichlids that are on the mellow side (Apistogramma, keyhole cichlid). Just give caves and line-of-sight breaks so breeding moods dont turn into drama.
- Peaceful livebearers or rainbows on the smaller side (platies, smaller Melanotaenia) in a roomy tank - they can match the lambaris activity level without getting picked on.
Avoid
- Big predatory cichlids (oscars, green terrors, jaguar cichlids) - anything that sees a tetra-shaped fish as a snack. Lambari are basically bite-sized to them.
- Nippy fin-biters and hyper bullies (serpae tetra in small groups, tiger barbs, some danios when crowded). Lambari are peaceful, but they are still small and can get stressed and shredded.
- Slow fish with fancy fins (bettas, fancy guppies, longfin angels). Even if the lambari arent trying to be mean, fast schooling fish can end up harassing or fin-pecking the slowpokes just by being in their face all day.
Where they come from
Doce River moenkhausia (Moenkhausia doceana) are little characins from Brazil, from the Rio Doce basin. Think warm, planty river margins and slower runs where there are leaves, roots, and insects dropping in. That background explains a lot: they like company, they like cover, and they eat like typical opportunistic tetras.
In a lot of places these get sold under the general "lambari" label. Try to buy a group that all look the same and came in together, because mixed batches can behave a bit differently and make breeding ID a headache.
Setting up their tank
Give them space to shoal and zip around, plus some broken sightlines so they dont spend all day bickering. I treat them like a slightly more assertive small tetra: not a monster, but not a delicate wallflower either.
- Tank size: 20 gallons long (75 L) is a nice starting point for a proper group, bigger is easier
- Group size: 10-12+ is where they settle down and look their best
- Flow: moderate. They enjoy a bit of current but dont need a river-tank blast
- Temp: mid 70s F is a sweet spot (around 24-26 C)
- pH and hardness: theyre flexible if you keep things stable. Slightly acidic to neutral is a safe aim
For decor, I like dark substrate, leaf litter (catappa or oak), and a tangle of wood. Add hardy plants around the edges (crypts, swords, vallis) and keep a clear lane in the middle for swimming. Floating plants help too, especially if your lights are strong.
A lid helps. Theyre not the worst jumpers, but a spook at feeding time can send one airborne.
What to feed them
They eat like most moenkhausia: always hungry, always ready. If you only feed flakes, theyll live, but youll get better color and calmer behavior if you mix in some real protein.
- Staples: quality flake or small pellet (they take pellets readily once they learn)
- Frozen: daphnia, cyclops, brine shrimp, chopped bloodworms (not every day)
- Live (if you can): baby brine shrimp, grindal worms, mosquito larvae
- Plant matter: theyll pick at spirulina flake and it seems to help keep them from chewing soft plants
Go easy on rich foods like bloodworms if your tank runs warm and you feed heavy. These fish can get a bit chunky, and overfeeding shows up fast as bloat and messy water.
How they behave and who they get along with
In a big enough group, theyre busy but not nasty. In a small group, they get nippy and spend too much time sorting out pecking order. Youll see quick little shoves and short chases, especially around food.
- Good tankmates: other medium-small, active fish that can handle some energy (other tetras, pencilfish, larger rasboras, peaceful barbs), Corydoras, small-to-medium plecos
- Use caution with: long-finned fish (fancy guppies, slow angels, bettas). Fin sampling is a real possibility
- Avoid: very timid fish that will hide all day, and tiny shrimp if you want them to reproduce
Theyre also fast at feeding time. If you keep them with slower bottom feeders, spread food around or drop a little after lights-out so the Corys and loaches get their share.
Breeding tips
Theyre egg scatterers. If youve bred other tetras, the playbook is similar: condition the adults well, give the eggs somewhere to fall, and keep the parents away from them because they will absolutely snack on their own eggs.
- Set up a small breeding tank (10-15 gallons) with a sponge filter and dim light
- Use a spawning mop, marbles, or a mesh grate so eggs drop out of reach
- Condition with live/frozen foods for a week or two
- Add a pair or a small group in the evening, then check for eggs the next morning
- Remove adults right after you see eggs or spawning activity
Ive had better hatch rates with slightly softer water and the lights kept low. Even just floating plants and a dark background can make a difference.
Fry are tiny at first. Infusoria, rotifers, or powdered fry food gets you through the first days, then baby brine shrimp is the growth switch. Keep water clean with small, frequent water changes and a gentle sponge filter.
Common problems to watch for
Most issues I see with these come from three things: not enough of them (so they turn into fin-nippers), pushing food too hard, or letting water quality slide because theyre active eaters.
- Fin nipping: almost always improves with a bigger group and more cover
- Ich after shipping: they can be stressy new arrivals. Keep temperature stable and dont rush tankmate introductions
- Bloat/constipation: back off rich foods, add daphnia, and dont feed big meals every time
- Skittishness: bright lights and bare tanks do it. Add floaters, wood, and plants
- Worn mouths or split fins: can happen if decor is sharp or if the group is too small and they spar constantly
If you see one fish getting singled out (torn fins, always hiding), pull it to a quiet recovery box or spare tank. These guys can dogpile a weak fish if the pecking order gets stuck.
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