Boeseman's rainbowfish

1) Where they come from

Boeseman’s rainbows are from a pretty small patch of the world—West Papua (Indonesia), mainly around the Ajamaru Lakes area. That’s part of why they got so popular and also why you’ll sometimes see talk about “true” Boesemani vs. mixed rainbow strains. In the wild they’re basically built for warm, clear-to-slightly-stained freshwater with lots of plant growth and open swimming space.

2) Setting up their tank

Give them room. These fish look “medium-sized” at the store, but a settled-in adult male is a chunky, fast-moving torpedo. If you cram them into a short tank, they’ll still live, but you won’t get the color or the relaxed schooling behavior you bought them for.

• Tank size: I’d start at 75 gallons (4-foot tank) for a proper group. A 55 can work short-term or with a smaller group, but it feels tight once they mature.
• Group size: 6 minimum, 8–12 is where they really shine. More fish = less bossiness.
• Temp: 76–80°F (24–27°C). They’ll handle a bit cooler/warmer, but mid-to-upper 70s keeps them active and colorful.
• pH/hardness: They’re pretty flexible. Mine have done great around neutral to slightly alkaline. Stable beats chasing a number.
• Flow/oxygen: Moderate flow and good surface agitation. They’re energetic swimmers and appreciate “fresh” water.
• Layout: Plants around the edges, open lane down the middle. They like cover, but they also like to sprint.

Filtration-wise, think “clean river/lake feel.” I run strong bio-filtration and do regular water changes. If nitrates creep up, you’ll usually see it in faded color and less enthusiasm at feeding time.

3) What to feed them

Boesemani are easy to feed, but they look their best with variety. If you only do one flake forever, they’ll survive… but the blues and oranges don’t pop the same, and you’ll notice it in fin condition too.

• Daily staples: quality flakes or small pellets made for community fish (they’re not picky).
• Color/condition boosters: frozen brine shrimp, mysis, daphnia, and good-quality krill-based foods (not every day, but regularly).
• Live foods (if you’re into it): baby brine shrimp, grindal worms, daphnia—great for conditioning and breeding.
• Greens: they’ll pick at some algae and fine plant bits, but I still like tossing in a spirulina flake now and then.

4) Behavior and tankmates

They’re active, curious, and always “on the move.” Males will flash at each other—side-by-side, fins up, showing off. It looks dramatic, but it’s usually harmless as long as you’ve got enough space and enough fish to spread the attention around.

• Best vibe: a big, bright community tank where they’re the main swimmers in the middle/top.
• Good tankmates: other rainbowfish (similar size), peaceful barbs, larger tetras, danios, Corydoras, bristlenose plecos, peaceful loaches.
• Use caution with: long-finned slow fish (they can get stressed by the constant zooming), very small shrimp (snack-sized), and super timid fish that hate commotion.

5) Breeding tips

They’re egg scatterers and they’ll spawn pretty readily once settled. The catch is: they also have zero shame about eating eggs and tiny fry, and so will most community tankmates.

• Easiest method: set up a separate breeding tank (even 20–30 gallons) with a sponge filter and a big spawning mop or dense fine-leaf plants.
• Conditioning: feed heavy on frozen/live foods for a week or two. You’ll see males intensify in color and chase females more.
• Spawning: they lay small adhesive eggs over multiple days, usually in the morning.
• Egg/fry strategy: either pull the mop daily to a grow-out container, or move the adults out after a few days.
• First foods: infusoria/microworms for the tiniest fry, then baby brine shrimp. Growth takes off once they’re on BBS.

6) Common problems to watch for

Most issues I’ve seen with Boesemani aren’t weird diseases—they’re “setup” problems: too small a tank, too few fish, or water that’s slowly getting grungy. Fix the environment and the fish usually bounce back fast.

• Faded color / clamped fins: often stress from cramped quarters, being kept in too small a group, or poor water quality.
• Ich after purchase: they’re not uniquely ich-prone, but they’re frequently shipped and stressed. Quarantine new fish if you can.
• Fin nips: usually from mixing them with nippy species or keeping a lopsided sex ratio in a small group.
• Jumping: open-top tanks + startled rainbowfish = disaster.
• Wasting away: watch for internal parasites in new arrivals (stringy white poop, weight loss despite eating).