Size, Diet, Tankmates & Breeding

I still remember the first time I saw Boesemani Rainbowfish (Melanotaenia boesemani) gliding in an aquarium – those neon blue fronts and vivid orange tails absolutely stunned me.

Their vibrant colors and graceful movements instantly made them a centerpiece in any tank, sparking my passion for keeping these remarkable fish. Caring for these beauties is a rewarding experience, whether you’re a seasoned hobbyist or just starting out.

This guide will walk you through everything you need to know to create a thriving environment for your Boesemani Rainbowfish, ensuring they flourish and continue to dazzle with their iridescent hues.

Species Summary

These rainbows hail from Indonesia’s western New Guinea (Lake Ajamaru and nearby lakes in West Papua), and belong to the rainbowfish family Melanotaeniidae. In fact, these schooling fish are prized as a pet for medium-sized community aquariums.

The male Boesemani really steal the show with that brilliant orange coloration on the back half of their bodies, while females remain a paler silver-blue (and are a bit smaller).

Because they’re social by nature, I always keep a small school – usually 6 or more of them – so the boys have plenty of girls to show off to, and so they all feel comfortable (a lonely rainbow is a shy rainbow!).

Tank Setup and Requirements

Setting up an aquarium for Boesemani rainbows is straightforward once you know their wild habits.

These fish come from clear, mildly alkaline mountain lakes and streams with lots of vegetation, so I like to densely plant the tank with live plants (Java fern, Vallisneria, Amazon sword and the like), plus driftwood and rocks for interest.

At the same time, I leave plenty of open swimming space – boesemani love to cruise back and forth along the length of a long tank. In practice, that means a nice long tank (at least 4 feet or ~50 gallons) to let a school of 6–8 fish stretch out.

Author Note: These rainbows are active mid-to-top level swimmers, so make sure the tank has a secure lid to prevent any jumping escapes.

Fish & Tank Size

I recommend a medium-sized community aquarium of roughly 50–75 gallons when keeping a Boesemani group. Because they can reach 3–4 inches long, each fish needs room to swim freely. If you’re not too sure about your tank’s volume, try our Aquarium Volume Calculator.

Personally, I use a 4–5 ft long tank for a school of six; if I had 10–12 fish I’d bump up the size even more.

Remember, they’re schooling fish: aim for at least six Boeseman’s together (ideally with slightly more females than males) so the males don’t stress a single female and can flash their colors at multiple ladies.

Water Parameters

Boesemani Rainbowfish are pretty hardy as long as you keep the water clean. In my tank I maintain these parameters:

• Temperature: 75–82°F, stable. They’re tropical, so I run a heater to keep it in that range.
• pH: Neutral to slightly alkaline (~6.5–8.0). In the wild their lakes hover around 6.4–7.8. They’re tolerant, but I aim for about pH 7.0.
• Hardness: Moderately hard water (8–20 dGH) helps mimic their native calcium-rich lakes. If your tap water is soft, I add a remineralizer (like Seachem Equilibrium) or some crushed coral in the filter.
• Filtration & Water Changes: Big filters and frequent water changes are key. I run a good canister or power filter (gentle flow is fine), and do ~25% water changes weekly. High water quality (low nitrates) keeps Boeseman’s colorful and healthy. Frequent changes are especially important because these active fish produce a fair amount of waste.

Author Tip: If you are interested in a free and simple tool to track your tank maintenance, try AquaTrack. We developed it to help fellow aquarists keep their tanks in great shape!

Decorations and Plants

To mimic their natural habitat, I go heavy on plants and décor. I use a dark gravel or sand substrate (it really makes their colors pop) and populate the tank with live plants – Java fern, crypts, Vallisneria, and floating plants.

These not only look natural, but they give the Boesemani plenty of cover when they want privacy. Floating plants also diffuse bright light.

I include some driftwood and smooth rocks for contrast and hiding spots. Importantly, I always leave open patches so my rainbows can sprint and school.

Author Note: In essence, the tank should feel like a planted New Guinea lake with shaded banks and open swimming lanes.

Lifespan

Boesemani Rainbowfish are a long-term commitment, which is part of what makes them so rewarding. With proper care, they can live anywhere from 5 to 8 years, and some hobbyists even report individuals reaching 10 years in pristine, well-maintained tanks.

Clean water, a nutritious and varied diet, low stress levels, and a peaceful environment are the key factors that influence their longevity. Like many fish, their immune systems weaken with age, so consistent care becomes even more important as they get older.

In my experience, the brightly colored males tend to show their age earlier by fading slightly in color and slowing down – but with the right conditions, they remain active and healthy well into their senior years.

Types of Boesemani Rainbowfish

While most hobbyists mean “Boesemani Rainbowfish” (the classic blue-and-orange Melanotaenia boesemani) when they say boesemani, there are a few color variants and relatives worth noting.

Boesemani Rainbowfish (normal form)

The standard Boesemani Rainbowfish is the one we’ve been talking about. It has that striking half-blue, half-orange body. In captivity they reach about 4 inches for males and 3 inches for females.

Like I mentioned earlier, pet stores often sell them when they’re juveniles (~1 inch) looking quite washed-out. It can take almost a year of high-quality food and good care for young boesemanis to mature and develop the full bright orange coloration on the males.

In short, be patient! The payoff is a dazzling adult fish that’s much more colorful than the little ones you bought.

Albino Boesemani Rainbowfish

There’s also an albino strain of Boesemani Rainbowfish, which hobbyists sometimes call Albino Boesemani. These look exactly like regular boesemanis in shape and size, but lack melanin.

Their body is pale pink or yellowish, and their eyes are red. They behave just the same as normal Boesemani – schooling, feeding and tank requirements are identical.

Albinos can actually stand out beautifully against dark plants. If you see them in a fish store, just know they need the same care (same temperature, pH, diet, etc.) as the standard form – the only difference is their color.

Red Rainbowfish

“Red Rainbowfish” in the hobby usually refers to a related species from New Guinea, Glossolepis incisus. It’s not a color morph of boesemani but it’s often mentioned alongside them.

As the name suggests, Red Rainbows are very bright red, especially males. They get a bit larger (up to 5–6 inches) and need a big tank too. Care-wise they’re not too different: warm, clean water, and a school of their own.

You can keep Red Rainbows with Boesemani as tankmates because they like similar conditions. In general I view all these colorful New Guinea rainbows as part of the same community – just be sure everyone has plenty of space.

Compatible Fish Species

Peaceful Community Fish

Boeseman’s rainbows are generally peaceful, so I choose tankmates accordingly. In my community tank I commonly keep them with small tetras (like Neon or Cardinal tetras), rasboras, and danios – all fast, peaceful mid-to-top dwellers.

I also add a few dwarf gouramis or peaceful barbs (cherry barbs, for example) for variety. Corydoras catfish and small peaceful loaches are great bottom-dwellers that won’t bother them.

In short, any fast-moving, non-aggressive fish of similar size makes a good tankmate. Aquarium guides explicitly recommend schooling Boesemanis with Tetras, Corydoras, Gouramis, non-aggressive Barbs, and even other Rainbowfish species.

You’ll notice all these suggestions – peaceful, fairly active fish that occupy different niches in the tank. I personally have success with 7 Boesemanis, 6 neon tetras, 3 cory cats, and a couple of dwarf gouramis, all coexisting happily.

Other Rainbowfish Species

Since Boesemanis are themselves Rainbowfish (family Melanotaeniidae), mixing different rainbowfish species can work well.

For example, “New Guinea Rainbows” like the Blue Eye Rainbow (Pseudomugil luminatus) or Threadfin Rainbow (Iriatherina werneri) can share similar water needs. I’ll sometimes keep other medium-sized rainbows (like Melanotaenia lacustris or Glossolepis species) in the same large tank.

Author Note: The key is to choose ones of comparable temperament and not too much larger size. In all cases, though, keep all rainbowfish in groups of the same species – they’ll shoal together and it looks great.

Avoid Aggressive or Fin-Nipping Fish

On the flip side, I avoid any fish that might nip fins or bully. Tiger barbs, large cichlids (like Oscars), big goldfish, or aggressive Betta splendens are no-goes.

These aggressive or oversized species would stress or even injure the Boeseman’s long fins. Hobbyists warn against keeping rainbowfish with “aggressive or overly large” tankmates.

Also, a caution on tiny tankmates: Boesemanis will eat any shrimp or baby fish that can fit in their mouths. I once lost a few cherry shrimp when my Boesemanis treated them as a snack!

In fact, AquariumCo-Op notes that Boesemanis will eat cherry shrimp, baby fish, and anything else that fits. In short, skip the delicate invertebrates or micro-fish. Instead, stock the tank with robust community fish and maybe a few snails, but no defenseless shrimp.

Feeding

Boesemani Rainbowfish are omnivores that love a varied diet. I feed them 2–3 times a day, offering only what they can eat in a few minutes. Here’s my typical feeding regimen:

• High-Quality Staple Flakes/Pellets: I use a top-notch tropical flake or pellet food as the daily base diet. It should be rich in protein and vitamins – think of it like their multivitamin. Vitamin-enriched foods help keep those blues and oranges vivid.
• Frozen / Live Treats: Every few days I supplement with protein treats. Boesemanis go crazy for bloodworms, brine shrimp, and daphnia – essentially, small crustaceans and insect larvae. I keep packets of frozen bloodworms and baby brine shrimp in the freezer. Once a week, a live or thawed handful of these will perk them right up. (In particular, baby brine shrimp are a favorite and great for all-sized rainbows.) These meaty foods mimic what they’d hunt in the wild.
• Vegetable/Herb Matter: To balance it out, I also toss in some plant matter occasionally. A few slices of blanched zucchini, cucumber, or a bit of spirulina flake now and then give them vitamins and roughage. Rainbowfish will nibble on greens if offered.

I’ve noticed that Boesemani will eat absolutely anything small that moves – even tiny live fish fry if they can catch them – but I don’t feed adult live feeder fish because of disease risk.

Author Note: Stick to prepared and frozen foods or safe live treats. The combination of high-quality flake (with vitamins), plus occasional live/frozen insects and brine shrimp, keeps them energetic, beautifully colored, and healthy.

Breeding

Breeding Boesemani Rainbows is quite rewarding once they’re mature. Here’s the basic approach I use, based on typical rainbowfish techniques:

1. I set up a separate breeding tank (about 20+ gallons) with very soft, slightly acidic water (fish spawn more readily in slightly softer, softer water).
2. In that tank I include fine-leaved plants or a spawning mop (Java moss is ideal) – these give the female places to scatter her sticky eggs.
3. I select a ratio of about 2–3 females per male.
4. I condition them with extra nutrition beforehand: lots of live foods like daphnia or freshly hatched baby brine shrimp and high-quality flake to get them in breeding condition.
5. Often breeders will raise the temperature slightly (to about 78–80°F) to trigger spawning.
6. When the male is ready, he flares his fins and flashes those bright colors to court a female. The female then releases hundreds of tiny adhesive eggs among the plant leaves.
7. I then carefully remove the adult fish – if left in, there’s some risk of predation. (Interestingly, some sources say well-fed Boeseman’s might ignore their eggs, but I’d rather be safe than sorry.)
8. The eggs hatch in roughly 7–10 days under good conditions. Once they do, the fry are tiny – I start by feeding them infusoria or liquid fry foods, then transition to powdered fry food and eventually freshly hatched baby brine shrimp as they grow.

The fry are fully golden at first, and as they age the males will begin developing that signature orange color. It takes time and good water quality, but watching the Boesemani juveniles grow into vibrant adults is incredibly satisfying.

Conclusion

Caring for Boesemani Rainbowfish has been a blast for me. These Boeseman’s truly live up to their name – the lightning flashes of color and energetic schooling add excitement to any aquarium.

The keys are simple: a long, well-planted tank; stable tropical water; frequent water changes; and a nutritious varied diet (flakes + live/frozen foods rich in vitamins and protein). Give them a proper school and clean conditions, and they’ll reward you by flourishing in captivity.

They’re great rainbows for anyone from beginners to veterans: hardy, peaceful, and endlessly fascinating to watch. Happy fishkeeping – and enjoy those dazzling orange tails and shimmering blues for years to come!

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