Lambari (Mimagoniates rheocharis)

Where they come from

Mimagoniates rheocharis is one of those South American little characins that feels like it slipped under the radar. They come from southern Brazil, in small coastal drainages where the water is usually clear to lightly tea-stained and full of leaf litter, roots, and overhanging plants. Think shallow creeks with a bit of current, lots of insects falling in, and plenty of cover.

Setting up their tank

These are active little fish that look best when they have space to cruise and a few calmer zones to retreat to. A 20 gallon long works nicely for a group, but bigger always makes their behavior more natural. They get bolder the more you keep together.

• Tank size: I would start at 20 gallons long for a proper group; 30+ is even nicer.
• Group size: 8-12 is the sweet spot. Fewer and they tend to act jumpy.
• Filtration: a sponge filter works, but I like a hang-on-back or canister with the flow turned down or diffused.
• Flow: moderate is fine. Give them a current lane, but also plant thickets where the water is calmer.
• Scape: sand or fine gravel, leaf litter, wood/roots, and dense plants (or spawning mops). Floating plants help a lot.
• Lighting: not too bright unless you have floaters or tall plants to break it up.

Water-wise, aim for stable and clean. Mine did well in slightly acidic to neutral water. If your tap is harder, they can often adapt, but they will not tolerate dirty water or big swings. Regular water changes matter more than chasing a perfect number.

What to feed them

They are small-mouthed micropredators and they really come alive on tiny live and frozen foods. You can keep them on good dry food, but color and behavior pop more once they are getting the "bug" part of their diet.

• Daily staple: small micro pellets, quality flakes crushed between your fingers.
• Best frozen: daphnia, cyclops, baby brine shrimp, finely chopped bloodworms (sparingly).
• Best live: baby brine shrimp, grindal worms, microworms, small daphnia.
• Feeding rhythm: small amounts 1-2 times a day beats one big dump. They are quick and will overeat if you let them.

How they behave and who they get along with

In a group, they are constantly in motion and will posture a bit, especially males. It is more "showing off" than actual fighting. In too small a group or too bare a tank, they can get skittish and hide.

Tankmates should be peaceful and not too grabby at feeding time. They do great with other small, calm characins, pencilfish, and gentle bottom fish. If you are doing a biotope-ish setup, think small catfish and tiny tetras rather than big centerpiece fish.

• Good tankmates: small Corydoras, Otocinclus, small Loricariids, pencilfish, small tetras, hatchetfish (with a tight lid).
• Use caution: fin-nippy tetras, very fast feeding fish that outcompete them, or anything that sees them as snacks.
• Skip: larger cichlids, aggressive barbs, or fish that patrol the surface and stress them out.

Breeding tips

Breeding them is doable, but it goes smoother if you treat it like a "tiny egg scatterer" project. Adults will eat eggs and fry if they find them, so you need either heavy cover or a separate setup.

• Breeding tank: 10-15 gallons, air-driven sponge filter, gentle flow.
• Spawning media: thick java moss, fine-leaf plants, or acrylic yarn spawning mops.
• Conditioning: lots of baby brine shrimp, daphnia, and good dry food for 1-2 weeks.
• Pair/group: a trio (1 male, 2 females) works, or a small group if the tank is dedicated to breeding.
• After spawning: remove adults or move the mop/moss to a grow-out tank to save the eggs.

Fry are tiny, so plan food before you see them. Infusoria, vinegar eels, or commercially available liquid fry food gets you through the first stretch, then freshly hatched baby brine shrimp once they can take it.

Common problems to watch for

They are not especially fragile, but they are the kind of fish that complains fast if the tank is neglected. A lot of issues show up as hiding, clamped fins, faded color, or suddenly refusing food.

• Jumping: the number one preventable loss. Tight lid, always.
• Wasting/skinny fish after purchase: can be internal parasites. Quarantine and observe; treat if needed.
• Ich and other spotty stuff after shipping: stress-related. Stable temperature and clean water help a lot.
• Fin damage: usually from rough decor, netting, or a nippy tankmate rather than real aggression among themselves.
• Outcompeted at meals: they can starve in a community tank full of pigs. Feed smaller foods in multiple spots or target-feed.