Andrica moenkhausia

Where they come from

Moenkhausia andrica is one of those South American characins that slips under the radar because it looks like a "plain tetra" in bad shop lighting. In the tank though, a settled group has a really clean, silvery look and a busy, schooling vibe that feels very Amazon/Orinoco tributary to me.

They come from freshwater river systems with moving water, lots of leaf litter and roots along the edges, and the kind of tea-stained tint you get from botanicals breaking down. You do not have to run a blackwater tank, but that general "soft, clean, stable" feel is what they seem to like.

Setting up their tank

Give them swimming room first, then break up lines of sight with plants and wood. They are active midwater fish, and a cramped tank turns them from "schooling" into "bickering."

• Tank size: I would not do less than 20 gallons long for a real group. 29+ gallons is even nicer if you want them to look calm and coordinated.
• Group size: 10-12 is where the magic starts. 6 works, but they are spicier and less confident.
• Filtration: decent flow is a plus. Not a torrent, just enough to keep oxygen up and keep the water from feeling stagnant.
• Layout: open center, plants/wood around the edges. Floating plants help them settle.
• Substrate: anything is fine. Dark sand or fine gravel makes their colors pop and they act less skittish.
• Light: medium. Too bright with no cover makes them hug corners.

For water, aim for stable, clean freshwater with regular water changes. They will live in a pretty wide range, but I have had the best luck with slightly acidic to neutral water and moderate temps. If your tap is harder, keep it consistent and focus on maintenance rather than trying to force soft water with quick fixes.

What to feed them

They eat like most Moenkhausia: opportunistic little pigs that do best with variety. A good flake or small pellet is fine as a base, but you will notice better color and fuller bodies when you rotate in frozen and live foods.

• Staple: quality flake or micro pellets they can finish quickly
• Frozen: daphnia, cyclops, baby brine, mysis (chopped if needed), bloodworms as an occasional treat
• Live (if you can): baby brine shrimp, grindal worms, daphnia
• Plant-ish extras: a bit of spirulina flake now and then helps balance things

How they behave and who they get along with

In a good-sized group they are classic midwater schoolers: lots of back-and-forth, quick little feints, and occasional sparring that looks worse than it is. If you keep too few, one or two fish tend to get singled out and you will see more fin-nipping.

Tankmates are straightforward. Think other peaceful community fish that like similar water and will not intimidate them.

• Good matches: other medium tetras, pencilfish, hatchetfish (with a lid), corydoras, small plecos, otocinclus (once the tank is mature), peaceful dwarf cichlids like Apistogramma (with plenty of hiding spots)
• Use caution: long-finned fish like guppies, fancy bettas, and slow angels - nipping becomes tempting if the school is small or the tank is tight
• Avoid: aggressive barbs, big cichlids, anything that will treat them as snacks

Breeding tips

They are egg scatterers like many tetras. Spawning is doable, but raising fry takes some prep. If you just leave them in the community tank, they will eat the eggs and you will never see babies.

• Breeding tank: 10-20 gallons, bare bottom or a thin layer of dark sand
• Egg protection: a thick clump of java moss, spawning mops, or a mesh/grate so adults cannot reach eggs
• Water: slightly softer and a bit cooler for a water change trigger often helps, then warm back up
• Pair/group: a well-fed group with extra live/frozen foods for a week is my go-to; they often spawn in the morning after a big water change
• After spawning: remove adults the same day if you can

Common problems to watch for

They are not fragile, but they do not forgive sloppy water for long. Most problems I have seen were tied to stress from crowding, inconsistent maintenance, or bringing home fish that were already rough.

• Fin nipping: usually too small a group, too small a tank, or not enough cover
• Ich and other spotty outbreaks: often shows up after big temp swings or adding new fish without quarantine
• Bloat/constipation: from heavy dry foods and overfeeding - add daphnia and fast them for a day
• Mysterious losses: commonly low oxygen at night in warm tanks with lots of bio-load - add surface agitation and keep the filter clean
• Pale color and hiding: lights too bright, no cover, or they feel exposed - floating plants help a lot